COBOL Class Condition

CLASS condition tests whether the data in a variable belongs to a specific category of characters such as ALPHABETIC, ALPHABETIC-LOWER, ALPHABETIC-UPPER, NUMERIC, etc. It also verifies the data that belongs to a user-defined category coded by CLASS in SPECIAL-NAMES.

Syntax -

Class Condition Syntax

Parameters -

  • identifier-1 - Specifies the variable to validate.
  • NOT - used to validate the negate condition.
  • NUMERIC - Used to validate whether the data is numeric or not.
  • ALPHABETIC - Used to validate the data contains only A to Z (lowercase or uppercase) characters and a space.
  • ALPHABETIC-UPPER - Used to validate the data contains only uppercase A to Z characters and a space.
  • ALPHABETIC-LOWER - Used to validate the data contains only lowercase a to z characters and a space.
  • class-name - Used to validate the data contains characters listed in the CLASS definition of the SPECIAL-NAMES paragraph.

Valid class condition combinations for different data types -

Data Type in Declaration Valid class condition
Alphabetic ALPHABETIC
ALPHABETIC-LOWER
ALPHABETIC-UPPER
class-name
NOT ALPHABETIC
NOT ALPHABETIC-LOWER
NOT ALPHABETIC-UPPER
NOT class-name
Alphanumeric,
alphanumeric-edited,
numeric-edited		 ALPHABETIC
ALPHABETIC-LOWER
ALPHABETIC-UPPER
NUMERIC
class-name
NOT ALPHABETIC
NOT ALPHABETIC-LOWER
NOT ALPHABETIC-UPPER
NOT NUMERIC
NOT class-name
Decimal NUMERIC
NOT NUMERIC
Numeric NUMERIC
class-name
NOT NUMERIC
NOT class-name

Practical Example -

Scenario1 - Validating Alphabetic

05 WS-VAR1          PIC A(10) VALUE "MAINFRAME ".   
...

IF WS-VAR1 IS ALPHABETIC
    DISPLAY "Data is alphabetic"
ELSE
    DISPLAY "Data is not alphabetic"
END-IF
Result -   Data is alphabetic

Scenario2 - Validating Numeric value

05 WS-VAR2    PIC 9(02) VALUE 25.  
...

IF WS-VAR2 IS NUMERIC
    DISPLAY "Data is numeric"
ELSE
    DISPLAY "Data is not numeric"
END-IF
Result -   Data is numeric

Scenario3 - Validating custom class

SPECIAL-NAMES.
    CLASS ALPHA-NUMERIC IS 'A' THROUGH 'Z' '0' THROUGH '9'.
...
05 WS-VAR1          PIC X(10) VALUE "MAINFRAME1".
...

IF WS-VAR1 IS ALPHA-NUMERIC
    DISPLAY "Data is Alpha-numeric"
ELSE
    DISPLAY "Data is not Alpha-numeric"
END-IF
Result -   Data is Alpha-numeric