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Cobol programming language
COBOL (Common Business-Oriented Language) is a compiled programming language designed for business applications, particularly in finance and administrative systems, despite being considered outdated. Developed in 1959 as part of a U.S. Department of Defense initiative, COBOL has undergone multiple revisions and is now primarily used in legacy systems on mainframes. The language features an English-like syntax, is divided into four main sections (Identification, Environment, Data, and Procedure), and focuses on business data processing and reporting.
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Cobol programming language
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- 2. What is itall about? It is a compiled English-like computer programming language designed for business use. While the language has been updated over the years, COBOL programs are generally viewed as being outdated. Today, however, a majority of payroll, accounting and other business application programs still use COBOL
- 3. More About Itis Procedural, imperative, object-oriented Designed by Howard Bromberg, Howard Discount, Vernon Reeves, Jean E.Sammet , William Selden, Gertrude Tierney Developed by CODASYL File Extensions are .cbl, .cob, .cpy
- 4. Quick History Developedin 1959 by CODASYL (Conference on Data Systems Languages) to provide common business language for business applications It was created as part of a US Department of Defense effort to create a portable programming language for data processing. It was standardized in 1968 and has since been revised four times. The current standard is ISO/IEC 1989:2014.
- 5. Uses of cobol COBOL is primarily used in business, finance, and administrative systems for companies and governments. COBOL is still widely used in legacy applications deployed on mainframe computers, such as large-scale batch and transaction processing jobs. But due to its declining popularity and the retirement of experienced COBOL programmers, programs are being migrated to new platforms, rewritten in modern languages or replaced with software packages.
- 6. Developing Environments OpenCobol Tiny Cobol Z Cobol Cobol for GCC GCC Cevela MX Wildcat Cobol 12 Cobol 650
- 7. Syntax COBOL hasan English-like syntax, which was designed to be self-documenting and highly readable. Example: y = x; is rather represented with: MOVE x TO y Lacking a large standard library, the standard specifies 43 statements, 87 functions and just one class. COBOL is not case sensitive
- 8. Syntax – CodeFormat A condition in COBOL can be expressed as: IS x GREATER THAN y More complex conditions can be "abbreviated" by removing repeated conditions and variables. For example: IS a GREATER THAN b AND a GREATER THAN c OR a EQUALS TO d
- 9. Divisions of Cobol COBOLcode is split into four divisions Identification Environment Data Procedure (containing of sections, paragraphs and sentences)
- 10. Identification Division Thisis the primary section that gives an identity to the program COBOL is not case sensitive – we can write code in uppercase or lowercase letters PROGRAM-ID is the main phrase in this section that gives a unique name to programs. DATE-WRITTEN and DATE-COMPILED are used to denote documenting part of the program AUTHOR is the clause to specify the name of the programmer.
- 11. Margins The programlines are restricted to 80 column width In this also, there are column boundaries that play major role Columns 1 to 6 are meant for line numbers Column 7 is meant for comment. A star mark in this column, denotes that line is a comment Column 8 is called A margin. Columns 8 to 11 is called A area Column 12 is called B margin. Columns 12 to 80 is called B area Some statements must start from A area, and some other must start from B area. If margin rules are not followed, the compiler will issue a syntax error
- 12. Environment Division Thisis used to specify the computer types, special symbols and files related data. This can have CONFIGURATION SECTION and INPUT-OUTPUT SECTION. Configuration section can have the following. SOURCE-COMPUTER. TDM180. OBJECT-COMPUTER. TDM180. SEPCIAL-NAMES. - DECIMAL POINT IS COMMA, CURRENCY SIGN IS “$”. In some countries the decimal points is not a dot and the currency signs keep varying. Input-output section is mainly for file specifications. This is given at the end of the presentation.
- 13. Data Division Thisis used to declare variables, screens, parameters to other programs and file record descriptions. This can have file section, working-storage section, linkage section, screen section. If sections are not used, they can be omitted as well. But usually every program will have at least one variable declaration. Unlike other languages, ALL VARIABLES DECLARED IN A PROGRAM ARE GLOBAL VARIABLES.
- 14. Procedure Division Thisis the place where the program logic is coded. This can have user defined sections. Usually, this is segmented as multiple paragraphs. Each paragraph is a set of statements that can act as a function or procedure as used in other languages Since all variables are global, every variable is accessible from every paragraph within that program. Statement delimiter is dot. Procedure division para names must start in A area Procedure division statements must start in B area The program starts from the very first line of the procedure division till the statement STOP RUN is reached.
- 15. Variables Variables areto be declared in working-storage section Variables can be scalar, arrays, records, file descriptor records The name of variable can have alphanumeric, with first character as alphabet, and can have only dash (hyphen) in it. Hypen must be embedded The type of variable is determined by the picture clause 77 level variables are scalar variables; arrays and records are explained later in this presentation 77 var-1 picture 999. 9 stands for a single digit number. This is a 3 digit number 77 var-2 picture xxx. X stands for alphanumeric. This is a 3 character alphanumeric 77 var-3 picture S99.99 S sign for numeric variable stands for sign + or -. A dot in picture clause with trailing 9s will indicate the number of decimals. Dot stands for explicit decimal point
- 16. Simple User Input Accept is the verb to get values from user Accep1 n1. – This will get the values from user, from the cursor position Accept n1 from date. – This will give you the current system date into variable Accept n1 from time. – This will give you the current system time into variable
- 17. Simple Output Displayis the verb to display values of variables on screen Display n1. – This will display the values on screen, from the cursor position Display Blank screen. – This will erase the content of screen. This must be defined in screen section.
- 18. Conditions The relationaloperators as well as spelt out phrases can be used If a < b – this can be written as if a is less than b >, <, =, >=, <= are the available relational operators NOT, AND, OR are the logical operators Less than, greater than, equal to are the spelt out phrases If a is less than b then Do some thing Else Do the other way End-if.
- 19. Multiple Conditions Wecan use if-then-else if for multi level conditions To make it very simple, we can use evaluate verb Evaluate a When 1 perform para1 When 2 perform para2 When 3 perform para3 When other perform para4 End-evaluate
- 20. Syntax Comments SinceCOBOL 2002, *> was used to introduce inline comments, similar to C’s // functionality. *> using function of display DISPLAY 'Hello World'.
- 21. Example – HelloWorld! IDENTIFICATION DIVISION. PROGRAM-ID. HELLO-WORLD. PROCEDURE DIVISION. DISPLAY 'Hello, World'. STOP RUN.