isdigit : isdigit « ctype.h « C Tutorial

1. C Tutorial
2. ctype.h
3. isdigit

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

  int main(void)
  {
    char ch;

    for(;;) {
      ch = getchar();
      if(ch == '.'){
          break;
      }
      if(isdigit(ch)){
          printf("%c is a digit\n", ch);
      }
    }

    return 0;
  }

1
1 is a digit
2
2 is a digit
3
3 is a digit
f
.