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.

Please do provide your comments or reactions. You may also post your questions in the comments.

Cobol numeric & computational data types

What are different type of COMP fields in COBOl ? What is COMP ? What is COMP-1 ? What is COMP-3 ?

These are few of the most asked and uncomfortably answered question in cobol. Let's discuss this today. I will try my best to be as simple and explanatory as possible, along with examples.

• WS-NUM PIC (5) VALUE '12345' :

This is a numeric variable in cobol. This type of variable is stored in mainframe as display or character format. For the above variable, if we read it in HEX : its stored as " F1F2F3F4F5". It will occupy 5 bytes storage.

Note: These variables are not most efficient for numerical calculations. For any type of calculation they need to converted to binary or comp-3 format for calculations. Binary is more native to the system. Binary is approx. 5-8 times faster and occupies lesser space.

• Comp or BINARY (both are synonymous):

COMP is binary integer data. For binary numbers, 8 bits or 1 byte, will store unsigned values from 0 to 255 or signed values from -128 to +127.
S9(1) - S9(4) COMP is 2 byte integer (-32768 - +32767 , half word)
S9(5) - S9(9) COMP is 4 byte integer( full word) ;
S9(10) - S9(18)COMP is 8 byte integer(double word )
i.e. - 9(2) is same as 9(4); 9(5) is same as 9(9); 9(10) is same as 9(18) in terms of storage.

• COMPUTATIONAL-1 or COMP-1 : WS-NUM COMP-1

These are specified for internal floating-point items (single precision). COMP-1 items are 4 bytes long. The sign is contained in the first bit of the leftmost byte and the exponent is contained in the remaining 7 bits. The last 3 bytes contain the mantissa.

• COMPUTATIONAL-2 or COMP-2 : WS-NUM COMP-2

These are specified for internal floating-point items (double precision). COMP-2 items are 8 bytes long. The sign is contained in the first bit of the leftmost byte and the remaining 7 bits contain the exponent. The remaining 7 bytes contain the mantissa.

• COMPUTATIONAL-3 or COMP-3 (internal decimal)

This is the equivalent to PACKED-DECIMAL. Comp-3 stores data in a BCD "binary coded decimal" format with the sign after the least significant digit. This format is more storage and CPU efficient in case of numerical calcualtions.
Packed Decimal representation stores two decimal digits in one byte. A packed decimal representation stores decimal digits in each "nibble" of a byte. Each byte has two nibbles, and each nibble is indicated by a hexadecimal digit. For example, the value 12 would be stored in two nibbles, using the hexadecimal digits 1 and 2. The sign indication is dependent on your operating environment. On an IBM mainframe, the sign is indicated by the last nibble. The C indicates a positive value, and D indicates a negative value.

The mainframe can perform arithmetic functions on packed-decimal fields without having to convert the format. Storing numeric values in a packed-decimal format may save a significant amount of storage space. For example, on the mainframe the value 12,345 would be five (5) bytes in length (i.e. x'F1F2F3F4F5'). If the same information is stored in a packed-decimal (i.e. USAGE IS COMP-3) the field would be three (3) bytes in length (i.e. x'12345C').

Example for comp-3 size calculations :
PIC S9(7) COMP-3. Byte size = (7 + 1) / 2 = 4
PIC S9(5)V99 COMP-3. Byte size = (5 + 2 + 1) / 2 = 4
PIC S9(6) COMP-3. Byte size = (6 + 1) / 2 = 3.5, rounded to 4
Comp-3 fields reserve a nybble for the sign, even for "unsigned" values, so the following fields are still 4 bytes:
PIC 9(7) COMP-3. Byte size = (7 + 1) / 2 = 4
PIC 9(6) COMP-3. Byte size = (6 + 1) / 2 = 3.5, rounded to 4

There is an automated tool to calculate size for different comp variables in cobol. Click here
Hope you find the above post useful. Please do provide your feedback or comments, if you had any. You may also post any of your cobol queries in the comments.

Call and Link in cobol

What is the difference between Call and Link in COBOL?

To start with the most basic difference. LINK is not a COBOL statement, its a CICS verb. CALL statement is certainly inside the boundaries of COBOL language.

If you still comapre their performance then here is the detailed list of differences. Please keep in mind we will be comparing only Dynamic Call with Link.

Please do provide comments or reactions.

What is the difference between NEXT SENTENCE and CONTINUE ?

NEXT SENTENCE gives control to the statement following the next period.

CONTINUE gives control to the next (imperative) verb after the explicit scope terminator. (This is not one of COBOL II's finer implementations). It's safest to use CONTINUE rather than NEXT SENTENCE in COBOL II.

Example :
IF A > C
IF A > B
CONTINUE
ELSE
MOVE WS-A TO WS-B
END-IF
MOVE WS-C TO WS-B
END-IF.
MOVE WS-B TO WS-A

In the above example , once the CONTINUE is executed the control will be transfered to next imperative executable statement ( MOVE WS-C TO WS-B).

Whereas, If we use NEXT SENTENCE instead of CONTINUE then control gets transferred to the statement following the next Period (MOVE WS-B TO WS-A).

Hope this helps.
Please do comment if you have any further questions on this.

What is the difference between a COBOL subscript and an index ?

An index is defined with it's associated table using the INDEXED BY phrase. Itis a storage area generated by the compiler. It is a register item that exists outside the program's working storage. It is 4 bytes in length. You can’tdisplay an index. The SET statement sets up and down an index,PERFORM VARYING.

A subscript is a positive integer defined in working-storage. It's best to define it as S9(4) COMP. A subscript is changed using ADD, SUBTRACT, MOVE or PERFORM VARYING like any other numeric working storage variable.

For detailed queries on subscript and index click here.

Please do provide your comments or reactions.

Difference between static and dynamic call in COBOL

Hi,

Lets start with one of the most common questions for a cobol beginner.

What does static and dynamic call mean in COBOL?
How do we use these calls?
Which call is better Static or dynamic ?

Below is the answer for all your queries :
All about static and dynamic calls in cobol

Please do provide your comments or reactions for this post.

Thanks,
-Kaps

Cobol Queries

Hi,

Objective : The mere objective of this blog is to answers all type of cobol question being raised at a common place. If there is a question on cobol, then answer should be present here.

When I first started studying cobol. I rated it as one of the most human friendly computer language. Although it looked easy, it had to be studied. Once I got thru the basics, I started with coding. As I started coding from scratch. I learnt a lot more than I ever studied in the cobol hand book (& still learning). Where did I learn all that from. Yes, the answer is internet( google search, mainframe forums ).

The biggest difficulty I faced was: Whenever I had doubt, I had to search and browse thru all the search pages to get the exact reply. There I felt a necessity for a site which could have all those information regarding cobol queries.

Now, I want to create a blog, which could answer all your technical queries on cobol. The basic need is to have all sort of different queries with their respective replies at a single place. So that It's easier for guys like me to locate the answers. This could even be helpful for your mainframe, cobol interview preparation.

Rules:
I would just follow one rule to retain the simplicity in the blog.
One query/post.

Although I have started this blog. I need a lot of help from all the cobol experts. I am just a beginner in cobol. So please do give your experts comments on posts.

Thanks,
- Kaps.