Constants

Constants

• Constant की value fixed होती है |
• Constant किसी भी data type का हो सकता है |
• Constant को Literals भी कहते है |
• Constant Pointer भी होता है |

Syntax : 

const data_type variable_name = value (optional) ;

Types of Constant :

• Integer Constant
• Decimal Constant
• Octal Constant
• Hexadecimal Constant
• Floating-point / Real Constant
• Character Constant
• String Constant
• Preprocessor

With Examples

Constant Types	with Examples
Integer	eg. 2, 10, -2
Decimal (Integer)	eg. 2, 10, -2
Octal (Integer)	eg. 02, 010
Hexadecimal (Integer)	eg. 0x12, 0x1f
Floating-point/Real	eg. -2.4, 4.8
Character	eg. 'i', 'j'
String	eg. "Hello", "Hi"
Preprocessor	eg. #define a 5

Integer Constant Types:

1. Decimal Integer Constant
2. Octal Integer Constant
3. Hexadecimal Integer Constant

Integer Constants

• Integer Constant normal Variable की तरह काम करता है |
• Integer Constant positive (+) या negative (-) हो सकता है |
• Integer Constant की Range -32768 से 32767 तक होती है |

for eg.
Source Code :

#include <stdio.h>

int main(){

const int num = 5; // integer Constant
printf("integer constant value : %d", num);

return 0;

}

Output

integer constant value : 5

Character Constants

• Character Constant normal Variable की तरह काम करता है |
• Character Constant सिर्फ single character लेता है | |
• Escape Sequences के साथ भी character constant इस्तेमाल किया जाता है |

Escape Sequences	Explaination
\'	Single Quotation Mark
\"	Double Quotation Mark
\\	Backslash
\?	Question Mark
\a	Audible Bell
\b	Backspace
\f	Form Feed
\n	New line
\r	Carriage Return
\h	Horizontal Tab
\v	Vertical Tab

for eg.
Source Code :

#include <stdio.h>

int main(){
const char ch = 'H'; // character constant
const char escape[]= "Hello\tWorld"; // Escape sequence - Horizontal Tab and string constant

printf("Character constant : %c\n", ch);
printf("String constant : %s\n", escape);

return 0;
}

Output

Character constant : H
String constant : Hello      World

Floating-point Constant

• Floating-point Constant normal float variable की तरह ही काम करता है |
• Floating-point Constant में Decimal point (.) होता है |
• अगर Floatint-point Constant की value integer type की हो तो वो Decimal point (.) लेता है |

for eg.
Source Code :

#include <stdio.h>

int main(){
const float num1 = 5; // floating-point constant with integer value
const float num2 = 3.525984; // Floating-point constant

printf("Floating-point constant : %f\n", num1);
printf("Floating-point constant : %f\n", num2);

return 0;
}

Output

Floating-point constant : 5.000000
Floating-point constant : 3.525984

String Constant

• String Constant की value Double Quotation Mark (" ") के अंदर लिखी जाती है |
• String Constant Single और Multiple characters लेता है |
• String Constant Escape Sequences के साथ भी इस्तेमाल करते है |

for eg.
Source Code :

#include <stdio.h>

int main(){
const char str1 []= "H"; // String Constant with single character
const char str2 []= "Hello World"; // Normal String constant
const char str3 [] = "Hello\nWorld"; // String Constant with Escape Sequence

printf("String Constant with single character : %s\n", str1);
printf("Normal String constant : %s\n", str2);
printf("String Constant with Escape Sequence : %s\n", str3);

return 0;
}

Output

String Constant with single character : H
Normal String constant : Hello World
String Constant with Escape Sequence : Hello
World

Preprocessor Constant

• Preprocessor के साथ भी Constant value रख सकते है |

for eg.
Source Code :

#include <stdio.h>
#define a 5 // Constant value with preprocessor
#define b 10 // Constant value with preprocessor

int main(){

printf("Value of a  : %d\n", a);
printf("Value of b  : %d", b);

return 0;
}

Output

Value of a  : 5
Value of b  : 10