C语言isxdigit()库函数

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

int main () {
   char var1[] = "tuts";
   char var2[] = "0xE";

   if( isxdigit(var1[0]) ) {
      printf("var1 = |%s| is hexadecimal character/n", var1 );
   } else {
      printf("var1 = |%s| is not hexadecimal character/n", var1 );
   }

   if( isxdigit(var2[0] )) {
      printf("var2 = |%s| is hexadecimal character/n", var2 );
   } else {
      printf("var2 = |%s| is not hexadecimal character/n", var2 );
   }

   return(0);
}