Note for C Language - C By Vandana Verma

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C Language Introduction of C C is a structured programming language, able to work with all most all field or applications for general as well as scientific purpose. C is also identifying as MLL (Middle level language), because of its symbolic constant behavior. We can say it used some syntactical and grammatical rules which must be followed by users. All programs are created by some extra symbols and text and these text and symbols have their own meaning inside the C language. So it is necessary for users to follow the sequence of rule after follow the symbols and text in their own format. This is the reason to call it as MLL. In C language user can create multiple small unit of program (called procedure/thread) to combine them in a large program. All small programs called procedure have a proper structure to declare them as structured programming language. C is also defined as general purpose language which means it worked in scientific as well as commercial both fields together. C is a strongest typed language, used to develop any kind of system software and driver software of system. All the keywords of C language are accessed only by lower case, because it is a case sensitive language where the fixed type of data and functions are always produce in lower case. History of C language: The entire era when C was developed, is called as evaluation of programming language. Before the development of C, some different programming languages were used in market, such as COBOL, FORTRAN, and ALGOL etc. In this time some languages are worked on commercial and some are worked on scientific field but there were no common language for both fields. For example FORTRAN worked for scientific purpose and COBOL worked for commercial field. FORTRAN: FORTRAN was developed by John Backus and his team at IBM co. for its 701 computer, in 1957. COBOL: It was developed by a retired navy commander and mathematician named Gross hopper in 1951. This language was later worked at 1959 – 1960 by the committee of conference on data system language (CODSYL) as a joint effort of computer user manufacturer of USA government. BASIC: In this time, another language was introduced in commercial application but later it worked on educational field named BASIC which was define by Thomas Kurtz and implemented by John kamney at Dourth Mouth college, USA in 1964. PASCAL:

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This language was introduced in market on the name of a great mathematician named Blaise Pascal by Nicolus Wirth in 1971, At Fadral institute of technology in Zuric, Switzerland. ALGOL: ALGOL was another language which was designed for scientific purpose by a team of mathematician 1958 named ALGOL-58 and in 1960 it was again implemented as ALGOL-60. This period was introduced as a golden period for the development of C. In this queue some different language was also introduced by different programmers. They are: CPL (Combined/common programming language): It was introduced by Thomas Kurtz in 1966. The main purpose for the development of CPL was its need in general purpose concept, but the key concept of this language was very high, which make it complex and clumsy and not handled by end users. BCPL: To overcome the problem of CPL a language was introduced by Martin Richards in 1979 named BCPL. But the main purpose was not achieved by BCPL also. B (Beginners): On the concept of BCPL a language was developed by Ken Thompson in 1970. This language was developed with the enhance feature of BCPL. We can say B was the successor of BCPL and CPL both. C: This era of development was continued with the development of C language which developed by Dennis Ritchie in 1972 at AT &T Bell Laboratory. It worked as a complete general purpose language successfully used in commercial and scientific both fields. The invention of C was followed by an alphabetical sequence where next language was developed after ‘B’, so it introduced as C to continue the sequence of this order. K&R C: We can say C was introduced with enhancing feature of ALGOL, BCPL and B. And in 1978 it was extended by Dennis Ritchie and Brian Kernighan and introduced as K&R C. ANSI C: It was again implemented by ANSI in 1983 where some different keywords such as- volatile console were added into it and launched as ANSI-C which again modified with some extra features. C90/C99/C11: In 1990 ISO (International standard organization) also updated the features of C and launched it in 1990 as c-90. In 1999 ISO again updated it as C-99 and in 2011 it defined as C-11.

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Name of language Year Name of developers ALGOL 1960 ISO BCPL 1963 Martin Richard B 1970 Ken Thompson C 1972 Dennis Ritchie ANSI-C 1989 ANSI C-90 1990 ISO C-99 1999 C-11 2011 ISO John Kamny DATA TYPE: It is a way/mechanism to define the category of data. Data type precedes a variable or identifier and instructs the compiler with 2 things, they are: a) Size of memory allocated in the term of bytes through an identifier. b) Type of data or information, i.e valid for that particular variable or memory locations. Note :We all know that compiler behave like a programmer, which has a list of information that determine how many bytes of memory, it will allocate for which data type. In C language different data types are precede with compiler, which worked as a fundamental data type. It means these data type having a fixed length of size. But according to behavior, data type of C language described in 3 categories, including fundamental data type. They are:a) Primary/primitive/fundamental b) Derived/Secondary c) User define data type

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Data Type Primary Data Type Secondary Data Type User Define enum pointer typedef Array Integer struct union Real Character void Short (%sh) Int(%d) Long(%ld) float(%f) Double (%lf) Char(%c) char (%s)