ORGIN AND HISTORY OF COBOL PROGRAMING LANGUAGE
COBOL ( common business-oriented language) is a compiled English-like computer programming language designed for business use. It is imperative, procedural and, since 2002, object-oriented. 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. Most programming in COBOL is now purely to maintain existing applications.
COBOL has an English-like syntax, which was designed to be self-documenting and highly readable. However, it is verbose and uses over 300 reserved words. In contrast with modern, succinct syntax like
In the late 1950s, computer users and manufacturers were becoming concerned about the rising cost of programming. A 1959 survey had found that in any data processing installation, the programming cost US$800,000 on average and that translating programs to run on new hardware would cost $600,000. At a time when new programming languages were proliferating at an ever-increasing rate, the same survey suggested that if a common business-oriented language were used, conversion would be far cheaper and faster.
In April 1959, Mary K. Hawes called a meeting of representatives from academia, computer users, and manufacturers at the University of Pennsylvania to organize a formal meeting on common business languages. Representatives included Grace Hopper, inventor of the English-like data processing language FLOW-MATIC, Jean Sammet and Saul Gorn.
The group asked the Department of Defense (DoD) to sponsor an effort to create a common business language. The delegation impressed Charles A. Phillips, director of the Data System Research Staff at the DoD, who thought that they "thoroughly understood" the DoD's problems. The DoD operated 225 computers, had a further 175 on order and had spent over $200 million on implementing programs to run on them. Portable programs would save time, reduce costs and ease modernization.
In COBOL 2002, Areas A and B were merged to form the program-text area, which now ends at an implementor-defined column.
COBOL 2002 also introduced free-format code. Free-format code can be placed in any column of the file, as in newer programming languages. Comments are specified using
Type safety is variable in COBOL. Numeric data is converted between different representations and sizes silently and alphanumeric data can be placed in any data item that can be stored as a string, including numeric and group data.In contrast, object references and pointers may only be assigned from items of the same type and their values may be restricted to a certain type.
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| GRACE HOPPER |
COBOL was designed in 1959 by CODASYL and was partly based on previous programming language design work by Grace Hopper, commonly referred to as "the (grand)mother of COBOL". It was created as part of a US Department of Defense effort to create a portable programming language for data processing. Intended as a stopgap, the Department of Defense promptly forced computer manufacturers to provide it, resulting in its widespread adoption.It was standardized in 1968 and has since been revised four times. Expansions include support for structured and object-oriented programming. The current standard is ISO/IEC 1989:2014.
COBOL has an English-like syntax, which was designed to be self-documenting and highly readable. However, it is verbose and uses over 300 reserved words. In contrast with modern, succinct syntax like
y = x;, COBOL has a more English-like syntax (in this case, MOVE x TO y). COBOL code is split into four divisions (identification, environment, data and procedure) containing a rigid hierarchy of sections, paragraphs and sentences. Lacking a large standard library, the standard specifies 43 statements, 87 functions and just one class
WHAT LEAD IT TO DEVELOPE
In April 1959, Mary K. Hawes called a meeting of representatives from academia, computer users, and manufacturers at the University of Pennsylvania to organize a formal meeting on common business languages. Representatives included Grace Hopper, inventor of the English-like data processing language FLOW-MATIC, Jean Sammet and Saul Gorn.
The group asked the Department of Defense (DoD) to sponsor an effort to create a common business language. The delegation impressed Charles A. Phillips, director of the Data System Research Staff at the DoD, who thought that they "thoroughly understood" the DoD's problems. The DoD operated 225 computers, had a further 175 on order and had spent over $200 million on implementing programs to run on them. Portable programs would save time, reduce costs and ease modernization.
CODE FORMAT
COBOL can be written in two formats: fixed (the default) or free. In fixed-format, code must be aligned to fit in certain areas. Until COBOL 2002, these were:| Name | Column(s) | Usage |
|---|---|---|
| Sequence number area | 1–6 | Originally used for card/line numbers, this area is ignored by the compiler |
| Indicator area | 7 | The following characters are allowed here:
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| Area A | 8–11 | This contains: DIVISION, SECTION and procedure headers; 01 and 77 level numbers and file/report descriptors |
| Area B | 12–72 | Any other code not allowed in Area A |
| Program name area | 73– | Historically up to column 80 for punched cards, it is used to identify the program or sequence the card belongs to |
In COBOL 2002, Areas A and B were merged to form the program-text area, which now ends at an implementor-defined column.
COBOL 2002 also introduced free-format code. Free-format code can be placed in any column of the file, as in newer programming languages. Comments are specified using
*>, which can be placed anywhere and can also be used in fixed-format source code. Continuation lines are not present, and the >>PAGE directive replaces the / indicatorDATA TYPES
Standard COBOL provides the following data types:| Data type | Sample declaration | Notes |
|---|---|---|
| Alphabetic | PIC A(30) | May only contain letters or spaces |
| Alphanumeric | PIC X(30) | May contain any characters |
| Boolean | PIC 1 USAGE BIT | Data stored in the form of 0s and 1s, as a binary number |
| Index | USAGE INDEX | Used to reference table elements |
| National | PIC N(30) | Similar to alphanumeric, but using an extended character set, e.g. UTF-8 |
| Numeric | PIC 9(5)V9(5) | May contain only numbers |
| Object | USAGE OBJECT REFERENCE | May reference either an object or NULL |
| Pointer | USAGE POINTER |
Type safety is variable in COBOL. Numeric data is converted between different representations and sizes silently and alphanumeric data can be placed in any data item that can be stored as a string, including numeric and group data.In contrast, object references and pointers may only be assigned from items of the same type and their values may be restricted to a certain type.
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