Introduction to C

C is a mid-level structured oriented programming language, used in general-purpose programming,developed by Dennis Ritchie at AT&T Bell Labs , the USA, between 1969 and 1973.

• C was invented to write UNIX operating system.
• C is a successor of 'Basic Combined Programming Language' (BCPL) called B language.
• Linux OS, PHP, and MySQL are written in C.
• C has been written in assembly language.

C program to print Hello!

            #include < stdio.h >
            int main()
                {
                    printf("Hello, World!\n");
                }
        

        
OUTPUT
Hello, World!

Tokens

In C programs, each word and punctuation is referred to as a token. C Tokens are the smallest building block or smallest unit of a C program.
The compiler breaks a program into the smallest possible units and proceeds to the various stages of the compilation, which is called token.

• Identifiers
• Keywords
• Constants
• Strings
• Operators
• Special Symbols

Identifiers

Identifiers are names given to different entities such as constants, variables, structures, functions, etc.

Rules for naming Identifiers

• An identifier can only have alphanumeric characters (a-z , A-Z , 0-9) (i.e. letters & digits) and underscore( _ ) symbol.
• Identifier names must be unique
• The first character must be an alphabet or underscore.
• You cannot use a keyword as identifiers.
• Only the first thirty-one (31) characters are significant.
• It must not contain white spaces.
• are case-sensitive.