In this article keywords in C Programming we give the information about Each C word is classified as a keyword or identifier. All keywords have a definite meaning and these meanings cannot be changed.

Keywords in C Programming:

  • Each C word is classified as a keyword or identifier. All keywords have a definite meaning and these meanings cannot be changed.
  • Keywords work as the basic building blocks for program statements. A list of all C keywords is given in the table.
  • All keywords only be written in lowercase letters. There are 32 keywords in Csuch as Follow


double int struct


else long switch
case enum register



extern return


const float short



for signed void


goto sizeof


do if static



  • Use of Identifier such as to the names of variables, functions and arrays. These are use-defined names and contain a sequence of letters and numbers as the first character.
  • You can used uppercase and lowercase letters are allowed, but lowercase letters are commonly used.
  • Underscore characters are also allowed in the identifier. It is commonly used in long indicators as a link between two words.

Rules for identifiers:

  • The first letter should be in alphabetical order.
  • An identifier can only consist of letters, numbers and underscores.
  • The first 31 characters of the identifier
  • Cannot use keywords.
  • There should be no white space.

Character set:

  • The characters are mostly used to create words, numbers, and expressions depend on the computer on which the program is run. However, there is a subset of characters available that can be used on most personal, micro, mini and mainframe computers.
    The characters in C are divided into the following categories:
    2. Digit
    3. Special character
    4. White spaces

The compiler enters the white space as long as they are not part of the string constant. White space can be used to separate words, but is restricted to characters between keywords and identifiers

Letters A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
A b c d e f g h I j k l m n o p q r s t u v w x y z
Digits 0 1 2 3 4 5 6 7 8 9
Special Characters ~ ! @ # $ % ^ & * ( {} | <> ?
White Spaces Blank Space, Tab, Carriage return, new line

C token:

  • In a piece of text, individual words and punctuation are called tokens. Similarly, the smallest individual items or units in a C program are known as C tokens.
    C has six types of tokens as shown in the picture. C programs are written using tokens and language syntax.

Constants in C Programming:

  • Constants in C refer to fixed values that do not change during program execution.
  • Constant refers to fixed values that the program cannot change.
  • Constants can be any original data type.

C has two types of constants:

  1. Numerical constant
  2. Character constant

Backslash character constant:

  1. Supports special backslash character constants used in C output functions.
  2. These character combinations are known as escape sequences.
Constants Meaning
‘\a’ Audible alert
‘\b’ Back Space
‘\f’ Form Feed
‘\n’ New Line
‘\r’ Carriage Return
‘\t’ Horizontal Tab
‘\0’ Null Character
‘\” Single Quote

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