Concepts:

Statements/Clauses:




Conditions

A condition is a special piece of code that allows you to instruct the computer to compare two pieces of data. Conditions are used in IF statements and in the While/Until clauses of the PERFORM statement

Conditions have the syntax:

data-1 operator data-2

where data-1 and data-2 can be a literal or a field. data-2 can also be a COBOL literal such as SPACES or ZEROS.

Operator can be the traditional comparison symbols =, <, >, <=, >=. To check for inequality use 'NOT =' since not all compilers accept the symbol <>. Rarely, a compiler will not accept <= or >=. You can use 'NOT >' and 'NOT <' instead. To comply with older versions of COBOL English can be used (i.e. EQUALS, IS NOT EQUAL TO, etc.).

Conditions can be combined into a compound condition by using AND and OR. Unless directed to do otherwise by grouping conditions with parenthesis COBOL will evaluate the ANDs first, then the ORs. If the conditions also contain NOTs then those are evaluated before the ANDs.

Also see 88-level Fields.


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Continuation

Statements can be continued over several lines without doing anything more than placing the code on separate lines. The compiler will figure it out.

Very long alphanumeric literals can be continued on multiple lines by placing a hyphen in column 7 of the continuation lines and placing the remainder of the literal there. This continuation of the literal requires a beginning single quote. The literal on the previous line does not have an ending single quote but is considered to extend to column 72.


             MOVE 'THIS IS ONE SERIOUSLY LONG ALPHANUME
      -    'RIC LITERAL' TO WS-STRING.

The hyphen on the 2nd line is in column 7. The single quote on that line is in column 12 and the literal continues from there. The ending single quote on that line is required. Note that the portion of the literal that's on the first line does not have an ending quote. If the last 'E' is not in column 72 then it will be assumed that all characters between that 'E' and column 72 are spaces and will appear in the literal.

Also valid with value clauses.


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Control Breaks

Control breaks are a feature of reports that allow for the grouping of and accumulating subtotals for data that belong together based on the value of a field (the control field). When the value for this field changes from one record to another the program "breaks" to do some special processing (like printing subtotals) before it goes on with the next record. The input file must be sorted on the control field(s).

An example of a report with a single-level control break:

      04/20/1999          The ABC Company              Page   1
                          Payroll Register

   Department: Janitorial

     Employee Nbr       Name          Hours      Rate        Pay

     123 45 6789   Ray, Marcus         40.0      2.00        80.00
     111 11 1111   Griese, Brian       50.0      2.50       125.00

   Totals for department Janitorial:   90.0                 205.00

   Department: Research and Development

     456 78 9123   Gates, Willy        12.0    800.00     9,600.00
	...            ...              ...     ...          ...

    Grand Totals:                   1,002.5             258,125.00

The control break is on department. Each control group (department) has it's own headings and footings (totals). Though it's not shown here in this example it's common for column headings to be repeated after each control heading.

See the algorithms page for sample code.


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Data Types

There are basically three types of data recognized by COBOL. Numeric data (both with or without decimal places: only 0-9, the decimal point and a sign allowed), alphabetic (only the characters A-Z) and alphanumeric (any characters). Alphabetic is rarely used.

Math can only be performed on numeric fields.


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Dates

Dates are common data for COBOL programs and must be manipulated often. Typically dates are stored in the Gregorian format, consisting of the familiar month, day and year. This is generally called the 'mmddyy' format, though the 'mmddyyyy' format is becoming the new standard (see the Y2K discussion page). While those formats are familiar to the coders and users dates are more often stored in 'yymmdd' or 'yyyymmdd' format so that they can be sorted easily.

So-called 'calendar math', where dates are used in calculations, can be a tedious process, unless your compiler supports the intrinsic date functions. If not, remember the following about the Gregorian calendar:

Also see Julian Dates.


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Delimiters

Delimiters are used as visual ends to a statement. They don't change processing but they do make code easier to read and maintain. An example of a delimiter is END-IF:

        IF WS-OSU > WS-MICHIGAN
           statement(s)
        ELSE
           statement(s)
        END-IF

Verbs that have end-delimiters are the comparison verbs (IF, EVALUATE), input/output (READ, WRITE, DELETE, REWRITE, ACCEPT), math (ADD, SUBTRACT, MULTIPLY, DIVIDE, COMPUTE), processing transfer (PERFORM, CALL) and some other lesser used verbs.

When the compiler encounters a period it takes that as the end of the statement. A delimiter that is found after a period is in error.


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Fields

A field is what other languages call a variable. It's a place to store data. All fields must be declared in the DATA DIVISION. A field declaration has three parts: the level number, the field name and the PIC clause. VALUE clauses are optional.

A valid field name is from 1 to 30 characters in length; contains only the letters A-Z, the digits 0-9 and the hyphen; contains at least one letter; does not begin or end with a hyphen; and is not a COBOL reserved word.

Also see Qualified Fields.


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HIGH-VALUES/LOW-VALUES

These are special numeric literals inherent to COBOL. HIGH-VALUES is the COBOL equivalent to infinity - no number is greater than HIGH-VALUES. Conversely, no number is less than LOW-VALUES.

They can be used in VALUE clauses, conditions and MOVE statements but math cannot be performed using these literals.


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Julian Dates

Julian is a date format that's an alternative to Gregorian dates. It consists of a 3-digit day and a year; there are no months. The days range from 1 (Jan 1st) to either 365 or 366 (Dec 31), depending on if the year is a leap year or not. This is generally known as the 'dddyy' or 'dddyyyy' format, even though normally the date is stored as 'yyddd' or 'yyyyddd' to ease with sorting.

Shops that make use of Julian dates will have callable routines that covert Julian to Gregorian and back again, because humans are comfortable with Gregorian dates. Intrinsic date functions available with newer COBOL compilers have these conversions built-in.

Julian format has two advantages. First, it's smaller, so it takes up less space. Second, it eases with some calculations because it contains no months. For example, how many days are between Feb 5, 1997 and Nov 28, 1999? Convert to Julian (1997036 and 1999332) a quick subtraction gives 1026 days. Remember that 'borrowing' a year gives you 365 days.

Getting a future date or past date can also be easier with Julian. What date is 45 days before Apr 15, 1999? Convert it to Julian (1999105), subtract 45 to get 1999060) and convert back to Gregorian (Mar 1, 1999).


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Level Numbers

Level numbers are used to group fields in the Data Division. A field can then be defined as a collection of other fields. The higher the level number the lower in the heirarchy the field is. Normally, the field numbers 01, 05, 10, etc. are used. By spacing them out you leave yourself room in case a level needs to be added later. Valid level numbers are 0-49.

Each FD is required to have an 01-level field defined. This is the record definition. It can be broken down into smaller fields if desired. For example:

        01  INPUT-RECORD.
            05  IN-EMPLOYEE-NUMBER     PIC 9(09).
            05  IN-EMPLOYEE-NAME.
                10  IN-EMP-LAST-NAME   PIC X(30).
                10  IN-EMP-FIRST-NAME  PIC X(15).
                10  IN-EMP-MIDDLE      PIC X.
            05  IN-BIRTH-DATE.
                10  IN-BIRTH-DD        PIC 99.
                10  IN-BIRTH-MM        PIC 99.
                10  IN-BIRTH-YEAR.
                    15  IN-BIRTH-CC    PIC 99.
                    15  IN-BIRTH-YY    PIC 99.
            05  IN-DEPARTMENT          PIC X(05).

We have an 01-level field that is broken down into 4 fields (the 05-level fields). Two of the 05-level fields are also broken down. Employee number is an elementary field because it is not broken down into smaller fields. The employee name and birth date are group level fields because they are broken down into smaller fields. Only elementary fields have PIC clauses.

The birth date is 8 characters long (the sum of the lengths of the elementary fields that compose it). All 8 characters can be accessed with one name (IN-BIRTH-DATE) or one of its pieces can be accessed by using that name instead (i.e. IN-BIRTH-MM).

A group level item 'ends' when another field with the same level number, or one with a lower value, is encountered. For example, the list of fields within IN-BIRTH-YEAR ends when the 05-level IN-DEPARTMENT is encountered. A field of level 10 would also have ended it.

All group level fields are considered to be alphanumeric.

All of these level number concepts are valid for WORKING-STORAGE also.

Also see 77-level Fields   88-level Fields.


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Literals

Literals are specific values as opposed to fields. Alphanumeric literals are enclosed in single quotes. In the following statements:

        MOVE 3.1415927 TO WS-PI.
        DISPLAY 'Enter a number: '.

3.1415927 is a numeric literal and 'Enter a number: ' is an alphanumeric literal. COBOL has some built-in literals like ZEROES and SPACES.

Also see Continuation   HIGH-VALUES/LOW-VALUES.


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Paragraphs

A paragraph is a section of COBOL code. Paragraph names start in the 'A' margin and follow the same naming rules that fields do. A paragraph ends when another paragraph name is encountered. Paragraphs can be executed with the PERFORM statement.

You can think of a pargraph as the equivalent of a subroutine in other languages. There are no arguments, all fields are thought of as global.

Also see Sections.


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PIC Clauses

PIC (short for PICture) clauses describe the size and type of data for each field. Numeric data has a PIC character of 9, alphanumeric data uses X and alphabetic data an A. Each 9, X or A represents one character. Length can also be represented by a repetition factor. The PIC clauses 9999 and 9(04) both define 4-digit numbers.

The PIC character V is used to mark where a decimal point is. If you had a 8-digit numeric field but 2 of the digits are after the decimal point, you would define it as PIC 9(06)V99. The decimal point is implied, it is not physically there in the data. It also takes up no space. To allow for a field to hold either positive or negative numbers precede the leftmost PIC character with an S (PIC S999V99).

There are several output PIC characters which help with formatting data for display or print. Numeric fields are MOVEd to fields defined with these formatting PIC characters. Fields defined with these formatting PIC characters are considered alphanumeric. No calculations can be done with these fields. Newer versions of COBOL allow these fields to be MOVEd to straight numeric fields.

To print a decimal point place a '.' in the desired place in the output PIC clause (i.e. PIC 999.99). You can place commas in output numbers also (i.e. PIC 999,999.99). In this manner the decimal point (and commas) do take up space. These are considered insertion characters - they insert themselves into the data. Other insertion characters are B (for a space), 0 (a zero) and / (useful in printing dates).

There is Z, for suppressing leading zeroes. If the digit represented by a Z is a leading zero it will print as a blank. You normally have one 9 in the PIC clause, in the one's place. All other digits represented by Z's. Do not use Z's after the decimal point. If used with commas (i.e. PIC ZZZ,ZZ9.99) a comma will only print if the character to its left prints, else it prints as a blank.

There are other zero suppression characters. A $ can be used just like the Z except that rightmost leading zero will print as a $ and all zeroes to the left of that will print as spaces. So the value of 125.00 MOVEd to a PIC $$$,$$9.99 will print as ' $125.00'. This behavior of the $ is called 'floating'. An * will work the same way (for check protection) but all * print, not just the one to the left of the most significant digit. When either the floating $ or the * is used in conjunction with commas the comma will only print as a comma if the character to its left prints as a digit. Depending on the situation it will otherwise print as a blank, $ or *.

For sign control you can use + or - as an output PIC character. A + will print + for positive numbers and - for negative numbers. A - will print a - for negative numbers and a blank for positive numbers. Either can be repeated to suppress leading zeroes (like the $) and can 'float' (also like the $). Alternatively, a + or - can be placed to the right of the number.

For accounting purposes the PIC characters 'DB' and 'CR' can also be used (i.e. PIC $$$,$$9.99DB). The DB or CR will only show if the value is negative. If positive they will print blanks.

Also see Blank When Zero   Truncation.


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Qualified Fields

It is legal in COBOL for different fields to have the same name. These fields cannot be 01-level fields and cannot be part of the same group-level field.

When referencing one of these fields the compiler requires the field to be qualified, meaning its group-level field must be specified. If both INPUT-RECORD and OUTPUT-RECORD contained a field named PAY-RATE then in code you cannot simply reference PAY-RATE, it would have to either be PAY-RATE OF INPUT-RECORD or PAY-RATE OF OUTPUT-RECORD.


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Reference Modification

Reference modification allows for the referencing of a portion of a field without having to make it a group-level field and defining each portion of the field that will be accessed.

If you wanted to check the value of the 4th through 6th characters of a field to see if they were equal to ABC you can code:

          IF WS-FIELD (4:3) = 'ABC'

The first number in the parenthesis represents the start position in the field and the second number represents the length. Both values have to be specified. COBOL treats all such references as alphanumeric.

Since this is not a self-documenting feature it should not be used carelessly.


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Reports

A report is simply a formatted representation of data, suitable for being printed on paper (hardcopy). Reports generically look like:

      04/20/1999          The ABC Company              Page   1
                          Payroll Register

     Employee Nbr       Name          Hours      Rate        Pay

     123 45 6789   Ray, Marcus         40.0      2.00        80.00
     456 78 9123   Gates, Willy        12.0    800.00     9,600.00
	...            ...              ...     ...          ...

    Totals:                         1,002.5             258,125.00

The first two lines are page headings, which will appear on every page. The next printed line (following the blank line) is column headings. It's common for column heading lines to be printed on every page. Next come the detail lines - typically one per record. At the end of the report will be a total line (if you are totalling anything). Note that the first detail line is the 6th line printed on a page (must count the blank lines also).

There are other types of lines that can appear on reports. Sometimes there are page footings (printed on the bottom of each page). There can also be report headings and report footings (only printed at the top and bottom of the report as opposed to each page).

Note the formatting of the data. There are commas and leading zeroes are suppressed on page numbers and monetary figures. The date has slashes. Always make reports as easy to read as possible.

See the algorithms page for sample code.

Also see PIC clauses.


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Sections

A section is a group of paragraphs. The section name must begin in the 'A' margin and be followed by the word 'SECTION'. Naming standards for sections are the same as those for paragraphs. A section ends when a new one begins.

A section can be PERFORMed in the same manner a paragraph is PERFORMed. The PERFORM only uses the section name, there is no reference to it actually being a section instead of a paragraph.


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Subscripts and Indexes

Subscripts and indexes are the two tools used to reference individual elements of a table. A subscript is a working-storage field defined separately from the table and is completely available to the programmer. An index is created automatically by the system if it is directed to do so and only has limited availability to the programmer.

An index cannot be part of a calculation, cannot be MOVEd to another field or cannot receive another field from a MOVE and it cannot be DISPLAYed. To manipulate an index the SET statement must be used.

The major difference between a subscript and an index is that a subscript is a position in the table (first element, 20th element, etc.). An index is a byte offset of an element relative to the beginning of the table. Since the first element is 0 bytes away from the start of the table, it has an index of 0. The 20th element (say each element is a PIC X(5)) starts 95 bytes from the start of the table so its index is 95. When manipulating an index the programmer does not do so by this byte offset. It is done by position in the table and the translation to byte offset is done internally by COBOL.

See the algorithms page for sample code on loading and searching tables.

Also see OCCURS clause,   Set.


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Tables

Tables are the COBOL equivalent to arrays. It is a set of fields with the same name and the same data type. To reference an individual element of the table a subscript or index must be used.

Tables are defined using the OCCURS clause.

See the algorithms page for sample code on loading and searching tables.


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Truncation

Truncation is a phenomenon that occurs when the receiving field of a MOVE or a math operation is not big enough to hold what it's getting. For alphanumeric fields truncation happens on the right (move 'COBOL' to a PIC X(4) and you get 'COBO') and numeric it happens on the left (move 1000005 to a PIC 9(06) and you get 5). No warnings, no messages. Just the loss of data.

Also see On Size Error.


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77-level Fields

A working storage field can be declared with a level number of 77. The 77 must be in column 8, the field cannot be a group-level field and the field cannot be part of a group-level field.


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88-level Fields

A field declared with a level number of 88 is commonly known as a 'condition name'. This name can be used anywhere a condition can be used and is generally more readable. Condition names are declared immediately after the field they are associated with. They use no storage (they take up no room).

For example your application contains a field named ACCT-TYPE which is PIC 999. One particular section of code determines if the account is a checking account (account type 100, 110, 210 or 300), a savings account (type 150 or 175) or a CD/IRA (type 400). An IF statement could look like:

            IF WS-ACCT-TYPE = 100 OR 110 OR 210 OR 300
               statement(s)
            ELSE
               IF WS-ACCT-TYPE = 150 OR 175
                  statement(s)
               ELSE
                  IF WS-ACCT-TYPE = 400
                     statement(s)
                  END-IF
               END-IF
            END-IF

Logically accurate but not entirely clear what account types are what. Comments would help, but condition names will help more. Define as:

        01  WS-ACCT-TYPE        PIC 999.
            88  CHECKING-ACCT           VALUE 100 110 210 300.
            88  SAVINGS-ACCT            VALUE 150 175.
            88  CD-IRA-ACCT             VALUE 400.

The same IF can now look like:

            IF CHECKING-ACCT
               statement(s)
            ELSE
               IF SAVINGS-ACCT
                  statement(s)
               ELSE
                  IF CD-IRA-ACCT
                     statement(s)
                  END-IF
               END-IF
            END-IF

Now it's self-documenting. The added advantage is if another type of savings account is developed it only needs added at the condition name. The IF statement doesn't change.

A specific value can appear in multiple condition names. Values associated with a condition name can be specified with THRU (i.e. VALUES 90 THRU 99). When checking condition names 'NOT' can be used. If a condition name only has one value a statement such as 'SET CD-IRA-ACCT TO TRUE' is valid and is the equivalent to 'MOVE 400 TO WS-ACCT-TYPE'.

Also see Set.


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Accept

The ACCEPT statement is used to get information from a source other than a data file (like the keyboard or CPU clock).

The statement:

        ACCEPT field.

will cause the program to wait until the enter key is pressed. Any data typed in before the enter key is pressed will then be placed in field. See How do I ...? for issues with getting numeric data in this manner. See the algorithms page for sample code on receiving and processing data received interactively.

The ACCEPT statement can also be used to get information from the system clock such as the current date and time:

        ACCEPT field-1 FROM DATE.
        ACCEPT field-2 FROM TIME.
        ACCEPT field-3 FROM DAY.
        ACCEPT field-4 FROM DAY-OF-WEEK.

Where:

Also see Delimiters.


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Add

The basic form of the ADD statement is:

        ADD value TO field-1.

which adds value (either a literal or a field) to field-1 and stores the result in field-1. A list of fields can follow the TO which will add the value to each of them. A list of values can be before the TO which would add all of them to field-1.

It is possible to add two values (either literals or fields) and store the result in a separate field with the GIVING clause:

        ADD value-1 TO value-2 GIVING field-1.

Also see Rounded,   On Size Error,   Truncation,   Delimiters.


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Blank When Zero

'BLANK WHEN ZERO' can be specified with a PIC clause so that blanks are printed if the value of the field is zero. For example, 'PIC -,--9.99 BLANK WHEN ZERO'.


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Call

The CALL statement is used to call another program. As long as the called program contains a GOBACK or EXIT PROGRAM then when the called program finishes control returns to the calling program.

Fields can be passed from the calling program to the called program. These fields are in the calling program's WORKING-STORAGE SECTION and in the called program's LINKAGE SECTION. The USING clause on the CALL specifies the fields to pass. The called program lists these fields in the USING clause of the PROCEDURE DIVISION. These fields don't have to have the same name in both programs, but the definitions must match.


            CALL 'PGM2.OBJ'.

            CALL 'PGM6F.OBJ'
               USING WS-FLD-1 WS-FLD-2 WS-FLD-3
                     WS-FLD-4 WS-FLD-5
            END-CALL.

See the algorithms page for sample code on calling another program.


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Close

The CLOSE statement will close an open file. Attempting to close a closed file will produce a run-time error.

One CLOSE statement can close multiple files.


        CLOSE file-name-1
              file-name-2.

Also see Open.


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Compute

COMPUTE allows you to combine several math operations in one statement, using familiar symbols instead of English-like sentances.

        COMPUTE field-1 = expression.

Expression is any valid mathematical expression involving literals, fields and the following symbols: + (add), - (subtract), * (multiply), / (divide), ** (exponentiation). To code 2 to the 3rd power use '2 ** 3'.

The order of operations is as follows:

  1. Exponentiation, from right to left
  2. Multiplication and division, from left to right
  3. Addition and subtraction, from left to right

Parenthesis can also be used to force the order in which the operations are carried out. Expressions inside parenthesis are computed first, from the innermost parenthesis to the outermost.

COMPUTE comes with a warning. Some compilers will round/truncate each intermediate result as opposed to waiting until the end of all calculations. This can lead to erroneous results.

Also see Rounded,   On Size Error,   Truncation,   Delimiters.


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Copy

COPY will insert the contents of the specified file into the program containing the COPY when the program is compiled. The file being copied is normally referred to as a copybook. COPYs can appear in any of the divisions. A period must terminate the COPY.

Record layouts are commonly in copybooks. Every program that reads or writes the file can contain a COPY instead of having the same record definition repeated in several programs. If the record layout is changed the change needs to be in one place and the programs recompiled to grab the more recent version.


         FD  IN-CUSTOMER-MASTER
             RECORD CONTAINS 1200 CHARACTERS.
         COPY CUSTMAST.

A specific location for the copybook can be specified on the COPY by using either 'OF' or 'IN', followed by the library name.


         FD  IN-CUSTOMER-MASTER
             RECORD CONTAINS 1200 CHARACTERS.
         COPY CUSTMAST OF CPYBOOKS.

COPY supports a REPLACING clause, where text in the copybook is altered once it is inserted in the program. The original copybook is unchanged. Literals and identifiers can be changed simply by specifying them in the command. Text can also be replaced, but requires the source and target text to be in between pairs of equal signs.


         COPY CUSTMAST REPLACING CUST-NUMBER BY CUST-NBR.

         COPY CUSTMAST REPLACING ==CUST-== BY ==CUSTOMER-==,
                                 ==9(5)==  BY ==X(5)==.

The first will change the name of a field, assuming it exists in the copybook. The second will change every occurrence of 'CUST-' to 'CUSTOMER-' and change all '9(5)' to 'X(5)'. Some record layout copybooks will have a dummy prefix on each field name and each time it is COPYed the prefix is changed by a REPLACING on the COPY. This allows for the copybook to used for multiple files in the same program - each COPY REPLACEs the dummy prefix with a different value avoiding having multiple fields with the same name.


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Corresponding

MOVE CORRESPONDING (or just MOVE CORR) is used with group-level fields. Whenever the source and target group-level fields have elementary fields of exactly the same name then that field will be moved. Consider the following:

     01  GROUP-1.                       01  GROUP-2.
         05  FIELD-A        PIC 999.        05  FIELD-E      PIC 99. 
         05  FIELD-B.                       05  FIELD-A      PIC 9(4).
             10  FIELD-C    PIC X(12).      05  FIELD-BB.
             10  FIELD-D    PIC XXX.            10  FIELD-C  PIC XXX.
         05  FIELD-E        PIC 99.             10  FIELD-D  PIC X.
         05  FIELD-F        PIC X.          05  FIELD-G      PIC X(10).

The statement 'MOVE CORRESPONDING GROUP-1 TO GROUP-2' will cause both FIELD-A and FIELD-E to be moved. FIELD-C and FIELD-D have different group-level names so they don't correspond.

This command is very useful when reformatting records. It can replace dozens, even hundreds, of moves.

Also see Move.


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Delete

DELETE will delete the current record in a non-sequential file OPENed as 'I-O'. There must be a current record, so a successful READ or READ NEXT must precede the DELETE.


        DELETE OT-FILE RECORD.

DELETE specifies the file name, followed by the word 'RECORD'.

See the algorithms page for sample code on using non-sequential files.

Also see Invalid Key.


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Display

The DISPLAY statement is used to show information on the terminal screen. Any combination of literals and fields can be displayed. All of the following are valid:

        DISPLAY field-name.
        DISPLAY 'Now performing paragraph 2000-READ'.
        DISPLAY 'Employee number = ' WS-EMPLOYEE-NBR.

Can use the clause 'WITH NO ADVANCING' after the value being displayed to prevent the cursor from dropping down a line on the screen. This can be useful for prompts for an ACCEPT statement:

        DISPLAY 'Enter a number: ' WITH NO ADVANCING.
        ACCEPT WS-NBR.

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Divide

The basic form of the DIVIDE statement is:

        DIVIDE value INTO field-1.

which divides value (either a literal or a field) into field-1 and stores the result in field-1.

It is possible to store the result in a separate field with the GIVING clause. When using GIVING you can opt to divide BY instead of divide INTO. This changes the positions of the divisor and dividend:

        DIVIDE value-1 INTO value-2 GIVING field-1.
        DIVIDE value-1 BY value-2 GIVING field-1.

You can also specify the remainder of the division to be stored in a separate field (only valid with GIVING):

        DIVIDE value-1 INTO value-2
           GIVING field-1
           REMAINDER field-2.

While it is legal in COBOL to have REMAINDER when not working with integers it makes little sense to do so.

Also see Rounded,   On Size Error,   Truncation,   Delimiters.


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Evaluate

The EVALUATE statement can be used to replace a nested- IF construct. It is the equivalent of a CASE or SWITCH statement of other languages.

            EVALUATE WS-GRADE
               WHEN 100
                  DISPLAY 'PERFECT'
               WHEN 90 THRU 99
                  DISPLAY 'A'
               WHEN 80 THRU 89
                  DISPLAY 'B'
               WHEN 70 THRU 79
                  DISPLAY 'C'
               WHEN OTHER
                  DISPLAY 'WOULD YOU LIKE FRIES WITH THAT?'
            END-EVALUATE.

Each 'WHEN' can only have one statement, though it can be a PERFORM. If multiple WHENs are true only the first one checked will execute. The 'WHEN OTHER' is like a 'none of the above'.

If two WHENs are 'stacked' (no statement between them) they are treated like an 'OR'. For example:

     
            EVALUATE WS-AGE
               WHEN 0 THRU 4
               WHEN 70 THRU 99
                  DISPLAY 'TAKE A NAP'
            END-EVALUATE.

The display will execute if WS-AGE falls in either range.

Instead of EVALUATEing a field you can use 'EVALUATE TRUE'. Each WHEN must then contain a condition. The first WHEN containing a true condition is executed. This method releases you from the restriction of checking the same field with each WHEN. Also valid is 'EVALUATE FALSE' where the first WHEN containing a false condition is executed.

Condition names cannot be used when EVALUATEing a field. Condition names can only be used with 'EVALUATE TRUE' or 'EVALUATE FALSE'. When EVALUATEing a field the WHENs contain values, not conditions.

Use EVALUATE ALSO to evaluate multiple fields/conditions at the same time.

     
            EVALUATE WS-SEX ALSO WS-MARITAL-STATUS
               WHEN 'F' ALSO 'S'
                  MOVE 'MISS' TO WS-TITLE
               WHEN 'F' ALSO 'M'
                  MOVE 'MRS.' TO WS-TITLE
               WHEN 'M' ALSO 'S'
                  MOVE 'MR.' TO WS-TITLE
               WHEN 'M' ALSO 'M'
                  MOVE 'POOR MR.' TO WS-TITLE
               WHEN OTHER
                  DISPLAY 'CALL SECURITY'
            END-EVALUATE.

You can use EVALUTE TRUE and FALSE with ALSO. Each WHEN will then contain one condition for each TRUE or FALSE.


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Exit

EXIT is used as the only statement in a paragraph that isn't supposed to do anything. This typically is used in conjunction with PERFORM THRUs. The paragraph being PERFORMed THRU is the one containing the EXIT.


          PERFORM 300-READ-FILE THRU 300-EXIT.

           . . . . . .

      300-READ-FILE.
          READ IN-FILE
             AT END MOVE 'Y' TO WS-EOF-SW
                    GO TO 300-EXIT
          END-READ.
             
           . . . . (MUCH LOGIC) . . . .
              
          PERFORM 400-WRITE-RECORD THRU 400-EXIT.
      300-EXIT.
          EXIT.      

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Exit Program

EXIT PROGRAM is used in a called program instead of a STOP RUN. It will return execution to the calling program where a STOP RUN will terminate all currently running programs.

Also see Goback.


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Go To

GO TO is used to transfer control to another part of the program. The target of a GO TO is a paragraph name.

Unlike a PERFORM a GO TO will not return when the paragraph finishes.


         GO TO 300-EXIT.

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Goback

GOBACK is used in a called program instead of a STOP RUN. It will return execution to the calling program where a STOP RUN will terminate all currently running programs.

Also see Exit Program.


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If

The IF statement is used to limit the execution of code so that it only happens under certain conditions. The standard form is:

        IF condition
           statement(s)
        END-IF.

The statement(s) are only executed if the condition is true. Each IF is allowed to have an ELSE. The statement(s) in the ELSE are only executed if the condition is false:

        IF condition
           statement(s)
        ELSE
           statement(s)
        END-IF.

There must be at least one statement in either portion of the IF. If you do not want any processing done you can use the CONTINUE or NEXT SENTENCE statement:

        IF condition
           CONTINUE
        ELSE
           statement(s)
        END-IF.

IFs can be nested (one IF inside another). COBOL will match an ELSE or an END-IF with the nearest IF that does not yet already have an ELSE or END-IF paired with it.

IFs can also be used to check types. An field can be checked to see if it contains valid numerics with:

        IF field IS NUMERIC

IS NOT NUMERIC is also valid. In the same manner a numeric field can be checked to see if IS POSITIVE, IS NEGATIVE or IS ZERO.

The END-IF delimiter is not required. A period will end all IFs.

Also see Evaluate.


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Initialize

The INITIALIZE command is used to set all of the values for fields in the same group-level field to either 0 or spaces, depending on the field's definition. The statement:

        INITIALIZE WS-GROUP.

where:

        01  WS-GROUP.
            05  WS-FIELD-1     PIC X(05).
            05  WS-FIELD-2     PIC 999.
            05  WS-FIELD-3     PIC S9(04)V99.
            05  WS-FIELD-4     PIC X(100).

is the equivalent to MOVEing SPACES to WS-FIELD-1 and WS-FIELD-4 and MOVEing ZEROS to WS-FIELD-2 and WS-FIELD-3. The nice thing is that as elementary fields are added to the group the INITIALIZE will automatically take care of them.

INITIALIZE will not change the value of any FILLER items. If a non-FILLER item has a VALUE clause it will still get either ZEROS or SPACES with the INITIALIZE statement. The VALUE is ignored.

Also see Move.


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Inspect

INSPECT has two purposes. It can count the number of times a particular character appears in an alphanumeric string, and it can change those characters to another.

          INSPECT field-1 TALLYING field-2
              FOR target.

Where field-1 is an alphanumeric field and field-2 is a numeric field that will hold the count.

target has a few different possibilities. It can be the word CHARACTERS in which case field-2 holds the number of characters in the alphanumeric string. Or a specific character can INSPECTed for using either ALL or LEADING followed by the character. Finally, any of these forms can be ended with a BEFORE/AFTER INITIAL clause:

          INSPECT WS-A TALLYING WS-N FOR ALL '*'
          INSPECT WS-A TALLYING WS-N FOR LEADING SPACES
          INSPECT WS-A TALLYING WS-N FOR CHARACTERS AFTER INITIAL SPACE
          INSPECT WS-A TALLYING WS-N FOR ',' BEFORE INITIAL '0'

To use INSPECT to change particular characters in an alphanumeric string, use REPLACING instead of TALLYING. The CHARACTERS, ALL and LEADING clauses are valid with REPLACING, as is FIRST. You can also use the BEFORE/AFTER INITIAL clause with REPLACING.

          INSPECT WS-A REPLACING ALL SPACES BY ZEROES
          INSPECT WS-A REPLACING FIRST 'A' BY 'B'
          INSPECT WS-A REPLACING ALL ' ' BY '0' AFTER INITIAL ','

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Invalid Key

The INVALID KEY clause is used with any type of non-sequential I-O statement. It specifies a statement to be executed if the command fails. Any statement such as READ or WRITE with any relative or indexed file should include this clause. For example:

       MOVE WS-KEY TO FILE-KEY.
       READ INDEX-FILE
          INVALID KEY PERFORM 300-RECORD-NOT-FOUND
       END-READ.

Upon an unsuccesful READ (for example, if no record in the file has that key) the specified statement is executed instead of the program crashing. There is an optional NOT INVALID KEY clause that can be included (must be after the INVALID KEY). It is best if only one statement is used in either the INVALID KEY or NOT INVALID KEY clause.

See the algorithms page for sample code on using non-sequential files.


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Merge

The merge is used to sort multiple files into one. Each of these files requires its own FD in the FILE SECTION, as does the combined file. All of these files must obviously have the same record format. The merge requires another entry in the FILE SECTION, an SD instead of an FD.

        MERGE sd-file-name ON ASCENDING KEY sd-field-name
             USING fd-input-file-name-1
                   fd-input-file-name-2
             GIVING fd-output-file-name

To sort multiple fields list them in the desired order. DESCENDING KEYs can be mixed with ASCENDING KEYs in the same MERGE (but only use 'ON' once). List the input files in the desired order in the USING clause.

Like the SORT an OUTPUT procedure can be specified (requiring a RETURN) instead of the GIVING, but the MERGE does not support the INPUT PROCEDURE option.


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Move

The MOVE statement is used to place a value in a field. It is kind of like an assignment statement in other languages though it does not allow for computations. Even though the statement is a move, it is more like a copy. The data is still in its original place as well as the receiving field. The standard form of statement is:

        MOVE value TO field.

where value can be a literal or a field. A list of fields can follow the TO causing the value to be MOVEd to each of the fields.

With a numeric move the source and destination are checked for the location of the decimal place (if one is not explicitly defined it is assumed to be to the right of the rightmost digit) and the move is done based on that. For example, MOVEing the value 80.375 to a PIC 9(06)V99 will cause the receiving field to contain 80.37 and MOVEing the value 3.1415927 to a PIC 9(08) will cause the receiving field to contain 3.

Alphanumeric and alphabetic moves first move the leftmost character of the sending field to the leftmost character of the receiving field, then the next character, and so on. All group-level MOVEs are considered alphanumeric.

If the receiving field is larger than the data being MOVEd then the field will be padded. Alphanumeric fields are padded on the right with spaces, numerics are padded on the left with zeroes. If a numeric has more decimal places than the data being MOVEd then zeroes will be padded on the right in the decimal portion of the receiving field.

Also see Truncation,   Corresponding.


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Mulitply

The basic form of the multiply statement is:

        MULTIPLY value BY field-1.

which multiplys value (either a literal or a field) by field-1 and stores the result in field-1.

It is possible to store the result in a separate field with the GIVING clause:

        MULTIPLY value-1 BY value-2 GIVING field-1.

Also see Rounded,   On Size Error,   Truncation,   Delimiters.


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Occurs

Occurs is used to define a table. It is followed by the number of elements in the table. COBOL does not support dynamic tables - the size must be specified.

        01  WS-TABLE.
            05  WS-ELEMENT   OCCURS 100 TIMES      PIC 9(5).

Defines a table with 100 elements. The allowable subscripts for this table are 1 through 100. To access a specific element of the table you would use something like WS-ELEMENT (27). A space is required before and after the parenthesis. The subscript can be a field but cannot be an expression. The subscript can be a separate working-storage numeric field or COBOL can told to create an index, like in the following:

        01  WS-TABLE.
            05  WS-ELEMENT   OCCURS 100 TIMES 
                             INDEXED BY WS-INDX       PIC 9(5).

The field WS-INDX is automatically created by COBOL.

The OCCURS can be on a group-level field which would then create a table containing multiple instances of each of the elementary fields. The OCCURS cannot appear on an 01-level field. It is also invalid on 77-level fields and 88-level fields.

        01  WS-TABLE-AREA.
            05  WS-TABLE         OCCURS 100 TIMES.
                10  WS-KEY             PIC XX.
                10  WS-VALUE-1         PIC 9(5).
                10  WS-VALUE-2         PIC 9(6)V99. 

This would create 100 elements of each of the 3 elementary fields.

        01  FILLER               VALUE 'MONTUEWEDTHUFRISATSUN'.
            05  WS-DAYS-OF-WEEK         OCCURS 7 TIMES.

Creates a table with 7 elements and also initializes them. This was not possible until a very recent version of COBOL. A redfines had to be used.

See the algorithms page for sample code on loading and searching tables.


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On Size Error

When used with one of the math verbs (ADD, SUBTRACT, MULTIPLY, DIVIDE, COMPUTE) it allows COBOL to detect truncation and divide-by-zero situations and execute a specified instruction instead of doing the calculation. The one statement can be a PERFORM. For example:

            DIVIDE WS-TOTAL BY WS-COUNT
                 GIVING WS-PCT ROUNDED
                 ON SIZE ERROR MOVE 0 TO WS-PCT
            END-DIVIDE.

A statement can also be specified for 'NOT ON SIZE ERROR'.


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Open

The open statement will open a file. Attempting to open an opened file will produce a run-time error. Accessing an unopened file will also produce a run-time error. You must specify whether the file is being opened as an input file or an output file.

Opening an existing file as output will cause the contents of the file to lost immediately after it is opened.

One read statement can open multiple files, even mixing input and output.


        OPEN INPUT file-name-1
                   file-name-2.

        OPEN OUTPUT file-name-1
                    file-name-2.

        OPEN INPUT  file-name-1
                    file-name-2
             OUTPUT file-name-3
                    file-name-4.

Also see Close.


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Perform

The perform statement will execute the specified paragraph and then control will return to the statement following the perform. There are no restrictions as to the physical placement of a paragraph compared to the perform statement that executes it.

There are several variations controlling the performing of paragraphs. A paragraph cannot perform itself; COBOL has no recursion.


        PERFORM paragraph-name.

        PERFORM paragraph-name
           WHILE condition.

        PERFORM paragraph-name
           UNTIL condition.

        PERFORM paragraph-name
           VARYING field-1 
           FROM value-1 BY value-2
           UNTIL condition.

        PERFORM paragraph-name value-1 TIMES.

Where any of the values can be literals or fields.

Each of the examples can also be specified with a THRU option, allowing for a sequence of paragraphs to be executed.


        PERFORM paragraph-name-1 THRU paragraph-name-2

Paragraph-name-2 will also be executed.

There is also what's known as an in-line perform where a block of code appears between a PERFORM and END-PERFORM. No paragraph name is specified. For example:

        PERFORM UNTIL WS-END-OF-FILE
           statement(s)
           READ IN-FILE
              AT END
                 MOVE 'Y' TO WS-END-OF-FILE-SW
           END-READ
        END-PERFORM

When using the UNTIL option with a perform or in-line perform the 'UNTIL condition' clause can be preceded by 'WITH TEST AFTER' to have COBOL check the condition after the loop instead of before. This will cause the loop to always be executed at least once. This has the effect of a REPEAT-UNTIL loop of other languages.

Also see Conditions   Delimiters   Sections.


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Read

The read statement will read the next record from the specified file and place the data in the record layout of that file's FD. The file must be already open as input. Reading an unopend file or attempting to read beyond the end of a file will produce a run-time error. The AT END clause is required.


        READ file-name
           AT END
              statement
        END-READ.

Optional clauses are NOT AT END and INTO. NOT AT END specifies a statement to be executed if the read did not hit the end of the file. INTO specifies a working-storage field into which the system will place the input record.


        READ file-name
           INTO
              working-storage field
           AT END
              statement
	   NOT AT END
              statement
        END-READ.

Also see Delimiters.


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Read Next

The READ NEXT is used after a successful START to read records along the established access path. The condition used by the START is not "remembered" by the READ NEXT so after each successful READ NEXT the record must be checked to see if it still matches whatever criteria the program is calling for. A successful read only means that a record was retrieved.

        READ indexed-file-name NEXT RECORD
           AT END statement
        END-READ

Since this is still a "sequential" process the READ NEXT requires an AT END clause. The optional NOT AT END clause is supported.

See the algortihms page for code examples.


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Redefines

The REDEFINES clause allows you to have multiple field definitions for the same piece of storage. The same data then can be referenced in multiple ways.

Take a simple example, useful for data validation:

          01  WS-NUMBER-X       PIC X(8).
          01  WS-NUMBER      REDEFINES WS-NUMBER-X
                                PIC 9(6)V99.

This portion of the data division only consumes 8 bytes of storage, not 16. Each of the two PIC clauses is describing the same 8 bytes of data, just doing it differently.

Once data is in WS-NUMBER-X it can be checked to see if it is numeric (IF WS-NUMBER-X IS NUMERIC). If so, WS-NUMBER can then be used as part of a calculation. If the data happens to be non-numeric then this type of code will prevent the program from choking. We access the data as alphanumeric (any data allowed) to see if it is safe to access it as numeric before actually attempting to do so.

Note that once the data was moved to WS-NUMBER-X it was also moved to WS-NUMBER because they both describe the same portion of storage.

There are a few rules with REDEFINES:


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Release

The RELEASE statment is required in an INPUT PROCEDURE of a SORT. It is used to specify that a record is to be included in the sort.

        RELEASE sd-record-name

        RELEASE sd-record-name FROM working-storage-field

Only RELEASEd records will be sorted.

See the algorithms page for sample code on using the SORT statement.

Also see Return.


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Return

The RETURN statment is required in an OUTPUT PROCEDURE of a SORT. It is used to retrieve a record from the sort back into your program.

        RETURN sd-file-name
           AT END
              statement
        END-RETURN

The records are RETURNed in the sorted order.

Like the READ statement the RETURN supports the NOT AT END and INTO optional clauses. Also like the READ, it is best if only one statement is used in either the AT END or NOT AT END clauses.

See the algorithms page for sample code on the SORT statement.

Also see Release.


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Rewrite

REWRITE will update the current record in a non-sequential file OPENed as 'I-O'. There must be a current record, so a successful READ or READ NEXT must precede the REWRITE. Following the READ/READ NEXT and before the REWRITE some information on the record will presumably be changed.


        REWRITE IN-FILE-REC.

REWRITE specifies the record, not the file.

See the algorithms page for sample code on using non-sequential files.

Also see Invalid Key.


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Rounded

Rounded is a clause valid with any of the math verbs (ADD, SUBTRACT, MULTIPLY, DIVIDE, COMPUTE). Place it in the command after the name of the field that will receive the result:


        ADD IN-AMOUNT TO WS-BALANCE ROUNDED.
        MULTIPLY IN-HOURS BY IN-RATE GIVING WS-PAY ROUNDED.
        COMPUTE WS-CUBE ROUNDED = WS-NBR ** WS-POWER.

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Search

The search command is used to search a table for a particular entry. The table must have an index (see OCCURS). The format is:


        SEARCH field
           AT END
                 statement-1
           WHEN  condition
                 statement-2
        END-SEARCH.

The field is the field with the OCCURS clause. WHEN specifies the condition on which to end the search (usually when some field equals a table entry) Only one statement can be specified in the WHEN but it can be a PERFORM. The AT END clause is optional, specifying one statement to be executed if the entire table is searched without satisfying the WHEN condition. It is recommended, however.

For example:


      * ALWAYS SET THE INDEX TO 1 BEFORE A SEARCH
           SET WS-INDX TO 1.

           SEARCH WS-TABLE
              AT END
                    MOVE ZEROES TO SALES-TAX
              WHEN  IN-STATE = WS-TABLE-STATE (WS-INDX)
                    MOVE WS-TABLE-TAX TO SALES-TAX
           END-SEARCH.

There can be multiple WHENs but the search stops once the condition of a WHEN is satisfied. To allow for multiple search matches use a PERFORM VARYING, which can increment an index.

If the table entries are sequenced by the field being searched then a binary search can be used instead. Use SEARCH ALL instead of SEARCH. It is more efficient than a regular search, especially with large tables. The SEARCH ALL has some limitations:

See the algorithms page for sample code on loading and searching tables.


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Set

Set can be used to manipulate an index:

        SET WS-INDX TO WS-NUMBER.
        SET WS-INDX UP BY 1.
        SET WS-INDX DOWN BY 3.

Note that while an index is actually a byte offset within a table COBOL does not expect you to work on that level. Setting an index to 2 will cause it to point to the 2nd element in the table, regardless of its offset. Likewise, seting an index up one will move it to the next element in the table, regardless of the size of the element. COBOL will translate it to the proper offset for you.

Set can also be used with condition names as an alternative to a MOVE. Consider the following:

        01  WS-END-OF-FILE-SW      PIC X  VALUE 'N'.
            88  END-OF-FILE               VALUE 'Y'.

It is then permissible to code:

        SET END-OF-FILE TO TRUE.

This is the equivalent to "MOVE 'Y' TO WS-END-OF-FILE-SW" but it is more readable. Most compilers will not allow a condition name with multiple values to be used in a SET. It is not a good idea in any case.


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Sort

The sort statement is used to sort a file. It requires a work file area that is defined in the FILE SECTION, just like any other file, except it is an SD instead of an FD. The basic sort statement looks like:

        SORT sd-file-name ON ASCENDING KEY sd-field-name
            USING fd-input-file-name
            GIVING fd-output-file-name

Multiple fields can be used in the sort, just list them in the desired order. DESCENDING KEY can be specified instead of ASCENDING KEY. DESCENDING KEY and ASCENDING KEY can be combined in the same statement.

The SORT statement will open and close both the input and output files automatically. The field(s) to be sorted on must be defined in the SD of the sort file.

An INPUT PROCEDURE can be specified instead of an input file. This allows the flexibility of selecting specific records to be sorted or to do other types of processing before the sort. Likewise, an OUTPUT PROCEDURE can be used instead of an output file. An INPUT PROCEDURE requires a RELEASE statement and an OUTPUT PROCEDURE requires a RETURN statement. For example:

        SORT sd-file-name ON ASCENDING KEY sd-field-name
            INPUT PROCEDURE IS paragraph-1
            OUTPUT PROCEDURE IS paragraph-2

This statement will execute paragraph-1, perform the sort and then execute paragraph-2. An INPUT PROCEDURE can be used with GIVING and an OUTPUT PROCEDURE can be used with USING. Each of these options allows the THRU option (i.e. paragraph-a THRU paragraph-b).

The clause 'WITH DUPLICATES IN ORDER' can be included in the statement (after the last ASCENDING/DESCENDING KEY). This will cause any records with the same value(s) for the sort field(s) to be kept in their original order. Not specifying this will not necessarily change their original order, but there is no guarantee.

See the algorithms page for sample code on using the SORT statement.


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Start

The Start statement is used to establish an access path for an indexed file with alternate keys (see the algortihms page for code examples). Note that keys in alternate indexes are not necessarily unique and the START is used in conjunction with the READ NEXT statement to find and retrieve and these records.


       START indexed-file-name
          KEY EQUALS alternate-key-field-in-FD
       END-START

The alternate key field must already be populated with a value.

The first record in the file with that value for the alternate key is read. It is a good idea to include a INVALID KEY clause in any START to handle the case where there is no record in the file with the appropriate alternate key.

Instead of 'EQUALS' the START also supports '>' and 'NOT <'.

With some compilers a START with an EQUALS will read a record if an appropriate one exists, but a START with a '>' or 'NOT <' will not retrieve a record under any circumstances. Other compilers will never have a START actually read a record.

See the algorithms page for sample code on using non-sequential files.


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Stop Run

The stop run statement will cause a normal termination to your program.


        STOP RUN.


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String

The STRING is used to concatenate (join) multiple fields or literals into one field. It replaces a series of MOVEs. For example:

       01  WS-DATE-FIELDS.
           05  WS-YEAR      PIC X(4)  VALUE '2000'.
           05  WS-MONTH     PIC XX    VALUE '12'.
           05  WS-DAY       PIC XX    VALUE '24'.
       01  WS-DISPLAY-DATE  PIC X(10).

    .....

           STRING WS-MONTH DELIMITED BY SPACE
                  '/'      DELIMITED BY SIZE
                  WS-DAY   DELIMITED BY SPACE
                  '/'      DELIMITED BY SIZE
                  WS-YEAR  DELIMITED BY SPACE
              INTO WS-DISPLAY-DATE.

After the above statement is executed WS-DISPLAY-DATE will contain '12/24/2000'. DELIMITED BY SPACE means to use as much of that field or literal that appears before the first space. If there are no spaces (like in the example) then the entire field or literal is used. Any character can be used in the DELIMITED BY clause.

Literals are usually DELIMTED BY SIZE, meaning to use the whole thing.

The DELIMITED BY character is never included in the combined field.

Also see Unstring.


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Subtract

The basic form of the subtract statement is:

        SUBTRACT value FROM field-1.

which subtracts value (either a literal or a field) from field-1 and stores the result in field-1. A list of fields can follow the FROM which will subtract the value from each of them. A list of values can be before the FROM which would subtract all of them from field-1.

It is possible to store the result in a separate field with the GIVING clause:

        SUBTRACT value-1 FROM value-2 GIVING field-1.

Also see Rounded,   On Size Error,   Truncation,   Delimiters.


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Unstring

The UNSTRING is used to split a field into multiple fields using a particular character to determine where to split the field. For example:

       01  WS-NAME-FIELDS.
           05  WS-FIRST      PIC X(10).
           05  WS-MIDDLE     PIC X.
           05  WS-LAST       PIC X(14).
       01  WS-WHOLE-NAME     PIC X(25)  VALUE 'HOMER J SIMPSON'.

    .....

           UNSTRING WS-WHOLE-NAME DELIMITED BY SPACE
              INTO WS-FIRST, WS-MIDDLE, WS-LAST.

The above statement will take the all of WHOLE-NAME, up to but not including the 1st space, and place it into WS-FIRST. The the part that is between the 1st and 2nd spaces, not including either one, is placed in WS-MIDDLE, and so on.

Also see String.


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Usage

USAGE can be used in conjunction with the PIC clause to specify how numeric data is to be stored. The most common options are DISPLAY (the default), COMP and COMP-3. COMP is short for COMPUTATIONAL, which can also be used. The words 'USAGE IS' are optional. USAGE is only valid with numeric fields. It can be specified as follows:

        01  WS-FIELDS.
            05  WS-DISPLAY-1         PIC 9(4).
            05  WS-DISPLAY-2         PIC 999     USAGE IS DISPLAY.
            05  WS-COMP-1            PIC S9999   USAGE IS COMPUTATIONAL.
            05  WS-COMP3-1           PIC 9(5)V99 COMP-3.

A number stored as COMP is in binary format. A COMP-3 number is stored as packed-decimal.


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Using

The USING clause is used to pass parameters from one program to another. It appears in the Call statement of the calling program to specify the parameter list. These parameters must be working storage fields.

The called program must have a USING clause on its PROCEDURE DIVISION statement followed by the parameters the program is receiving. These fields are defined in the LINKAGE SECTION of the DATA DIVISION, which follows the WORKING-STORAGE SECTION. All of the received fields are updateable by the called program.

The parameters do not have to have the same names in the calling and called programs but the sizes and data types have to match.

     (In calling program)

       CALL 'PGM2.OBJ'
         USING WS-FIELD-1, WS-FIELD-2, WS-FIELD-3
       END-CALL

     (In called program)

    PROCEDURE DIVISION USING LK-FIELD-A, LK-FIELD-B, LK-FIELD-C

See the algorithms page for sample code on calling one program from another.


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Value

Value allows you to initialize a field at the same time it is defined. The VALUE clause follows the PIC clause and must be the proper type of data. The value can be changed in code at any time.

           05  WS-NBR-LINES-PER-PAGE   PIC 99   VALUE 60.
           05  FILLER                  PIC X(6) VALUE 'PAGE: '.

Some compilers will require the VALUE data to be the proper size also, others will truncate to fit. Most compilers will not allow VALUEs in input FDs - it is a bad idea in any case.

Also see Continuation   Initialize.


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Write

The write statement will write data to the specified file. The file must be opened for output. Attempting to write to an unopened file or a file opened for input will produce a run-time error.


        WRITE record-name.

Optional clauses are FROM, BEFORE and AFTER. FROM specifies a working-storage field from which the system will select the data that is to be written. FROM can appear with either BEFORE or AFTER.

BEFORE and AFTER specify actions to be taken by the printer along with writing a record of data. You can either specify the number of lines that are to be advanced or you can specify advancing to the top of the next page. BEFORE and AFTER cannot appear in the same write.


        WRITE record-name
           FROM working-storage field
        END-WRITE.

        WRITE record-name
           AFTER ADVANCING value LINES
        END-WRITE.

        WRITE record-name
           AFTER PAGE
        END-WRITE.

Where value can be a literal or a field.

Also see Delimiters.


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