C library function - isdigit()

Description

The C library function void isdigit(int c) checks if the passed character is a decimal digit character.

Decimal digits are(numbers): 0 1 2 3 4 5 6 7 8 9

Declaration

Following is the declaration for isdigit() function.

int isdigit(int c);

Parameters

• c -- This is the character to be checked.

Return Value

This function returns nonzero value if c is a digit, else 0

Example

The following example shows the usage of isdigit() function.

#include <stdio.h>
#include <ctype.h>

int main()
{
   int var1 = 'h';
   int var2 = '2';
    
   if( isdigit(var1) )
   {
      printf("var1 = |%c| is a digit\n", var1 );
   }
   else
   {
      printf("var1 = |%c| is not a digit\n", var1 );
   }
   if( isdigit(var2) )
   {
      printf("var2 = |%c| is a digit\n", var2 );
   }
   else
   {
      printf("var2 = |%c| is not a digit\n", var2 );
   }
  
   return(0);
}

Let us compile and run the above program, this will produce the following result:

var1 = |h| is not a digit
var2 = |2| is a digit