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Lexicon of C programming language

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This article introduces you to various components of C- language statements .
C-Tokens are the essential part of  a C-compiler . A token is an individual entity of a C - program.C-statements having keywords , Identifiers , Constants , Strings , Operators and special symbols are called C-tokens.

CHARACTER SET in C language includes alphabets (used to write C -statements and character constans) ,  digits  (used to assign numeric data) , special symbols (used for special purposes such as to create relational statements and assignment statements). There are 30 special symbols like <,>,<=,>=,== and many others and at last are white spaces.

KEYWORDS and IDENTIFIERS

  Every word in C - language is a keyword or an identifier. Keywords cannot be used as a variable name , these are reserved words. For example: auto , break , case , else , struct  etc.
While Identifiers refer to name of user-defined variables , arrays , functions (we will discuss about arrays and functions  later in next articles). Identifiers should not start from a digit and are case - sensitive. For example : pay , roll_no , s , S etc.

CONSTANTS

Constants refer to fixed values that the program may not alter . Constants can be of any of the basic data type.These uses secondary storage area. Some valid constants are : 52.7 , -43.4 , " Gimibits" , 'M' etc.

VARIABLES

A variable is a value that can change at any time. It is a memory location used to store a data value .
* A variable name should be carefully chosen by the programmer so that its use is reflected in the entire program.
* It contains name of a valid identifier .

For example : area , simple , std1 etc.
A declaration begins with data type, followed by name of one or more Variables . For example ,
          int roll_no,marks;

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