Introduction to COBOL

COBOL

• stands for Common Business-Oriented Language

• one of the oldest high-level programming languages

• primarily used for business, finance, and administrative systems

• designed to be easily understood and used by non-technical people

Key COBOL Features

• global business language

• easy readability

• seamless integration with modern systems

• portable language

• evolving language

COBOL Program Structure

Sections (Program Structure)

logical subdivision of program logic

• a collection of paragraphs

Paragraphs (Program Structure)

subdivision of a section or division

• either a user defined or a predefined name followed by a period, and consists of zero or more sentences/entries

Sentences (Program Structure)

combination of one or more statements

• appear only in the Procedure division

• must end with a period

Statements (Program Structure)

performs some processing

Characters (Program Structure)

lowest in the hierarchy and cannot be divisible

Identification Division

• mandatory division

• this division is used to identify the program

• PROGRAM-ID is mandatory in this division

  • program name

  • consist of 1 to 30 characters

Environment Division

• specify input and output files to the program

• consist of two sections:

  • Configuration section

  • Input-Output Section

Configuration Section (Environment Division)

provides information about the system on which the program is written and executed

Consist of two paragraphs:

• Source Computer - system used to compile the program

• Object Computer - system used to execute the program

Input-Output Section (Environment Division)

provides information about the files to be used in the program

Consist of two paragraphs:

• File Control - provides information of external data sets used in the program

• I-O control - provides information of files used in the program

Data Division

used to define the variables used in the program

File Section (Data Division)

used to define the record structure of the file

Working-Storage Section (Data Division)

used to declare temporary variables and file structure which are used in the program

Local-Storage Section (Data Division)

• similar to Working-Storage section

• variables will be allocated and initialized every time a program starts execution

Linkage Section (Data Division)

used to describe the data names that are received from an external program

Procedure Division

• used to include the logic of the program

• consists of executable statements using variables defined in the data division

• last statement to end the execution should be STOP RUN or EXIT PROGRAM

Position 1-6

• column numbers

• reserved for line numbers

Position 7

• indicator

• can have an asterisk * indicating comments

• can have hyphen - indicating continuation

• can have slash / indicating from feed

Position 8-11

• area A

• COBOL divisions, sections, paragraphs and special entries begins in this area

Positions 12-72

• area B

• COBOL statements must begin in this area

Positions 78-80

• identification area

• can be used as needed by the programmer

Symbol 9

used for declaring numeric data type

Symbol A

used for declaring alphabet

Symbol X

used for declaring alphanumeric

Symbol V

used for declaring Implicit Decimal

Symbol S

used for declaring sign

Symbol P

used for declaring assumed decimal