isdigit c++
int isdigit ( int c );
Checks whether c is a decimal digit character.
A value different from zero (i.e., true)
if indeed c is a decimal digit. Zero (i.e., false) otherwise.
/* isdigit example */
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
int main ()
{
char str[]="1776ad";
int year;
if (isdigit(str[0]))
{
year = atoi (str);
printf ("The year that followed %d was %d.\n",year,year+1);
}
return 0;
}
/* Output */
The year that followed 1776 was 1777