C - Constant


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C Constant

  • A constant is a value that never changes.
  • Constant in C means the content whose value does not change at the time of execution of a program.
  • Constants are also called literals.
  • It is considered as the best exercise to define constants using only upper-case names.
C Constants

C Syntax

const type constant_name;

Types of Constant :

  • Integer Constant
  • Real constant
  • Character constant
  • Backslash character constant

Integer constant :

  • An "integer constant" is a decimal (base 10), octal (base 8), or hexadecimal (base 16) number that represents an integral value.
  • Integer constants are used to represent integer values that cannot be changed.

Example :

5, -265, 0, 99818, +25, 045, 0X6.

Real constant :

  • Constants in C are fixed value that does not change during the execution of a program
  • A real constant is combination of a whole number followed by a decimal point and the fractional part.

Example :

0.0083,   -0.75,   .95,   215.  

Character constant :

  • A character constant is a single alphabet , a single digit or a single special symbol enclosed within a pair of single quotes.

Example :

 ‘c’,  ‘5’,  ‘#’,  ‘>  ‘,  ‘Z’ 

Backslash character constant :

  • There are some characters which have special meaning in C language.
  • They should be preceded by backslash symbol to make use of special function of them.
  • C supports some special backslash character constants that are used in output functions.
\\ \ character
\' ' character
\" " character
\? ? character
\n New line Formation
\r Carriage return
\f Form feed
\a Alert or bell
\b Backspace
\v Vertical tab
\t Horizontal tab
\ooo Octal number of one to 3 digits
\xhh . . . Hexadecimal number of one or more digits

Sample - C Code

void main()
    const int SIDE = 5;
    int area;
    area = SIDE*SIDE;
    printf("The area of the square with SIDE: %d is: %d sq. units",SIDE,area);

C Code - Explanation :

  1. In C programming, const int SIDE =5 is a constant integer data type that specifies the side value as 5.
  2. In C programming, int is specified as integer data type with its variable name as area.
  3. In this example, here we are calculating area , where area=SIDE*SIDE .
  4. In this example, “The area of the square with SIDE” is represented as a printf statement , where %d is an integer datatype assigning the value of 5 with its unit as sq. unit

Sample Output - Programming Examples

  1. Here in this output “The area of the square with SIDE” is represented as a printf statement which is being called in the console window.
  2. Here in this output 5 specifies the integer variable.
  3. Here in this output 25 specifies the area square of integer value 5 .

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