Every programming language is designed with some system-defined set of characters, symbols, keywords, and standards. Similarly, COBOL has its own set of characters, symbols, keywords, and standards. Below are the basic and known terms in the COBOL –

• Character set
• Character strings
  • COBOL Words
  • Variables
  • Literals
  • Constants
  • Figurative Constants
  • Comments
• Separators

Character set -

The character set refers to the collection of valid characters that can be used within the language. These are used to define literals, variables, and other identifiers in a COBOL program.

The COBOL language has its own set of valid characters (78) that contains alphabets (A-Z | a-z), digits (0-9), and special characters. The list of basic COBOL characters are –

Character Strings

The character string is a set of characters created for a purpose or to name something. Character strings are used as -

• COBOL Words
• Variables
• Literals
• Constants
• Figurative Constants
• Comments

COBOL Words -

A COBOL word is a set of characters, and each character is from the character set - A to Z, 0 to 9, - (hyphen), _ (underscore). COBOL word minimum length is 1 character and maximum length is 30 characters.

COBOL Word Types -

COBOL words are two types and those are -

• User-defined Words - Any word coded by the developer in the program is considered as a user-defined word. For Example - MTHPROG1, STD-GENDER, ....
• Reserved Words - A reserved word is a system-defined word with proper meaning or task assigned in COBOL language. For Example - ACCEPT, SKIP1, ZEROS, ....

Variable -

A Variable is a data name used to hold the value for processing in the program. A Variable is also called as a data item. For Example - WS-A, WS-VAR, WS-TOTAL, WS-INPUT, WS_OUTPUT, etc. Every variable should declare in the DATA DIVISION of the COBOL program.

We will learn more about variable in the further topics.

Literal -

The literal is the value that is assigned to the variable. The value can be a string or number or a figurative constant. Literals are classified into two types –

• Non-numeric literals - Non-numeric literals are the strings enclosed by quotation marks(") or apostrophes('). It can contain all valid character that are allowed by COBOL.
  For Example - "HELLO", "THIS ISN'T WRONG", etc.
• Numeric literals - A numeric literal is a number that is a combination of a sign character (+ or -), and a decimal point. A numeric literal codes directly without quotation marks(" ") or apostrophes(' ').
  For Example - 1234, -1234, etc.

Constant -

A variable can be initialized with a literal. If the literal doesn't change during the program's execution, the variable is considered as a constant variable, and the value is considered as a constant value.

Constants are three types, and those are –

• Numeric constants – Numeric variables having one value throughout the program execution are called numeric constants. For example - 01 WS-PI PIC 9(2)V9(2) VALUE 3.14.
• Alphanumeric | non-numeric constants – Alphanumeric variables that have only one value throughout the program execution are called as alphanumeric constants. For example - 01 WS-HI PIC X(05) VALUE "HI".
• Figurative Constants - System-defined constants are predefined in the COBOL and used as replacement for standard values like spaces, zeroes, etc. For example - 01 WS-VAR PIC 9(5) VALUE ZEROES.

Figurative Constant -

Figurative constants are system-defined keywords with predefined values. The figurative constants in COBOL are -

Comments -

A comment is dummy statement that is used to provide information about code or requirements. All computer-supported characters are allowed to write a comment and it do not affect the execution of the program.

The comments are considered as three types based on their usage and where they are used -

• IDENTIFICATION DIVISION Comments - The entries with optional paragraphs are comments and their usage is -
  

         AUTHOR. NameOfProgrammer.
         INSTALLATION. Development-center.
         DATE-WRITTEN. mm/dd/yy.
         DATE-COMPILED. mm/dd/yy. HH:MM:SS.
         SECURITY. Program-type.

• Full line comments (any division) - Any line starting with an asterisk (*) in column 7 (indicator area) is considered as a full-line comment. For example -

  ----+----1----+----2----+----3----+----4----+----5
        * FULL LINE COMMENT WITH * IN COLUMN-7.

• An inline comment starts with a floating comment indicator (*>) in the middle of any line in between 8-72 columns. For example -

         01 WS-VAR        PIC X(12).    *> INLINE COMMENT   

Separators

A separator is a single or multiple character that separates words or strings. The below table shows the separators list -

Practical Example -

Scenario - Below screenshot describes the different types of character strings in COBOL programming.