isdigit c 2b 2b

1int isdigit ( int c );
2Checks whether c is a decimal digit character.
3  
4A value different from zero (i.e., true)
5if indeed c is a decimal digit. Zero (i.e., false) otherwise.
6
7
8/* isdigit example */
9#include <stdio.h>
10#include <stdlib.h>
11#include <ctype.h>
12int main ()
13{
14  char str[]="1776ad";
15  int year;
16  if (isdigit(str[0]))
17  {
18    year = atoi (str);
19    printf ("The year that followed %d was %d.\n",year,year+1);
20  }
21  return 0;
22}  
23
24/* Output */
25The year that followed 1776 was 1777

1str = "10"
2  
3//Evaluates to True
4isdigit(str[0])

1#include<stdio.h>
2#include<ctype.h>
3
4int main() {
5   char val1 = 's';
6   char val2 = '8';
7
8   if(isdigit(val1))
9   printf("The character is a digit\n");
10   else
11   printf("The character is not a digit\n");
12
13   if(isdigit(val2))
14   printf("The character is a digit\n");
15   else
16   printf("The character is not a digit");
17
18   return 0;
19}