String Manipulation in COBOL

A string refers to a sequence of characters. String manipulation operations include finding a particular character/sub-string in a string, replacing particular character/sub-string in a string, concatenating strings and segmenting strings. All these functions are handled by three verbs INSPECT, STRING and UNSTRING in COBOL. EXAMINE is the obsolete version of INSPECT supported in COBOL74.

INSPECT

• INSPECT- FOR TALLYING - It is used to tally the occurrence of a single character or groups of characters in a data field.
  Syntax:
  INSPECT identifier-1 TALLYING identifier-2 FOR ALL/LEADING literal-1|identifier-3 [BEFORE|AFTER INITIAL identifier-4|literal-2] - Optional.
  INSPECT identifier-1 TALLYING identifier-2 FOR CHARACTERS [BEFORE|AFTER INITIAL identifier-4|literal-2] - Optional.
  Main String is identifier-1 and count is stored in identifier-2. Literal-1 or Identifier-3 is a character or group-of-characters you are looking in the main-string. INSPECT further qualifies the search with BEFORE and AFTER of the initial occurrence of identifier-4 or literal-2.
  Example:
  WS-NAME - 'HELLO HOW ARE YOU DOING?'
  INSPECT WS-NAME TALLYING WS-COUNT ALL 'O'
  BEFORE INITIAL 'HOW' AFTER INITIAL 'YOU'
  END-INSPECT
  Result:
  WS-COUNT contains - 2
  

• INSPECT- FOR REPLACING : It is used to replace the occurrence of a single character or groups of characters in a data field.
  Syntax:
  INSPECT identifier-1 REPLACING ALL|LEADING literal-1|identifier-2 BY identifier-3|literal-2 [BEFORE|AFTER INITIAL identifier-4|literal-2] - Optional.
  INSPECT identifier-1 REPLACING CHARACTERS BY identifier-2 BEFORE|AFTER INITIAL identifier-3|literal-1
  

• INSPECT-FOR COUNTING AND REPLACING It is a combination of the above two methods. INSPECT identifier-1 TALLYING (tallying part ) REPLACING (replacing part)

STRING

STRING command is used to concatenate one or more strings.

Syntax:
STRING identifier-1 / literal-1, identifier-2/ literal-2 DELIMITED BY (identifier-3/literal-3/SIZE) INTO identifier-4 END-STRING.
01 VAR1 PIC X(10) VALUE 'MUTHU '
01 VAR2 PIC X(10) VALUE 'SARA '
01 VAR2 PIC X(20).
To get display 'MUTHU,SARA'
STRING VAR1 DELIMITED BY ' ' ',' DELIMITED BY SIZE VAR2 DELIMITED BY ' ' INTO VAR3 END-STRING.
The receiving field must be an elementary data item with no editing symbols and JUST RIGHT clause.
With STRING statement, specific characters of a string can be replaced whereas MOVE replaces the full string.
01 AGE-OUT PIC X(12) VALUE '12 YEARS OLD'.
STRING '18' DELIMITED BY SIZE INTO AGE-OUT. => 18 YEARS OLD.

Reference Modification - equivalent of SUBSTR

'Reference modification' is used to retrieve or overwrite a sub-string of a string. ':' is known as reference modification operator.

Syntax:
String(Starting-Position:Length)
MOVE '18' TO AGE-OUT(1:2) does the same as what we did with STRING command.
When it is used in array elements, the syntax is Array-element (occurrence) (Starting-Position:Length)

UNSTRING

UNSTRING command is used to split one string to many strings.

Syntax:

UNSTRING identifier-1 [DELIMITED BY (ALL/) identifier2/literal1 [,OR (ALL/) (identifier-3/literal-2),..]] INTO identifier-4 [,DELIMITER IN identifier-5, COUNT IN identifier-6] [,identifier-7 [,DELIMITER IN identifier-8, COUNT IN identifier-9]
01 WS-DATA PIC X(12) VALUE '10/200/300/1'.
UNSTRING WS-DATA DELIMITED BY '/'
INTO WS-FLD1 DELIMITER IN WS-D1 COUNT IN WS-C1
WS-FLD2 DELIMITER IN WS-D2 COUNT IN WS-C2
WS-FLD3 DELIMITER IN WS-D3 COUNT IN WS-C3
END-UNSTRING.
Result:
WS-FLD1 = 10 WS-FLD2 =200 WS-FLD3=300 WS-C1 = 2 WS-C2=3 WS-C3=3 WS-D1 = '/' WS-D2='/' WS-D3 ='/'
ON OVERFLOW can be coded with STRING and UNSTRING. If there is STRING truncation then the imperative statements followed ON OVERFLOW will be executed.

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