isdigit()

test for any decimal digit

Synopsis:

#include <ctype.h>
int isdigit( int c );

Description:

The isdigit() function tests for any decimal-digit character '0' through '9'.

Returns:

A nonzero value when the argument is a decimal-digit character, otherwise zero.

Examples:

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

char chars[] = {'A', '5', '$'};

#define SIZE sizeof( chars ) / sizeof( char )

void main()
  {
    int   i;

    for( i = 0; i < SIZE; i++ ) {
      printf( "Char %c is %sa digit character\n",
        chars[i],
        ( isdigit( chars[i] ) ) ? "" : "not " );
    }
  }

produces the output

Char A is not a digit character
Char 5 is a digit character
Char $ is not a digit character

Classification:

ANSI

See also:

isalnum(), isalpha(), iscntrl(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit()