C LANGUAGE – INTRODUCTION
The C Language was developed by Dennis Ritchie at AT & T’s Bell Laboratories in 1972. C is a middle level, procedure oriented programming language. C is more popular because, even today’s modern programming languages like java, C++ were all developed by using C language. C language is the base for all other programming languages.
Why C is called middle level language?
C is called middle level language as it stands between machine level language and high level language. C is capable of doing both system level programming to develop Operating System as well as High level programming to develop applications that run on the Operating systems.
C Language Standards:
The first edition of “The C Programming Language” was published by Brian Kernighan and Dennis Ritchie in 1978. This was an informal specification of C language and was referred by the name K&R C.
The American National Standards Institute(ANSI) formed a committee to establish a standard specification of C language in 1983. A standard version of C was formed in 1989 and was called “ANSI C” and also as “C89”. Later, in 1990, the ISO(International Organisation for Standardisation) adopted the ANSI C standard with some changes in formatting and was referred to as “C90”. Hence C89 and C90 denotes the same programming language.
In 1999, the C standard was revised to introduce new features like inline functions, variable length arrays, support for one line functions beginning with //, improved support for IEEE floating points etc. This standard is known as “C99”
C11 standard version was introduced in 2011 with various changes to C99 like Alignment specification, multi-threading support, etc.
C keywords are all lowercase, since uppercase and lowercase characters are not equivalent it’s possible to utilize an uppercase keyword as an identifier but it’s not a good programming practice.
Points to remember
1. Keywords can be used only for their intended purpose.
2. Keywords can’t be used as programmer defined identifier.
3. The keywords can’t be used as names for variables.
The standard keywords are given below: