/*
 * @(#) hex2int.c - Hex-to-integer simple converter.
 * (c) 1995 Ivan Maidanski <ivmai@chat.ru> http://ivmai.chat.ru
 * Freeware program source. All rights reserved.
 **
 * Language: ANSI C
 * Tested with: BSD GNU CC
 * Last modified: 1995-10-28 12:00:00 GMT+04:00
 */

#include <stdio.h>

int htoi(char* s) {
  int i=0;
  if (*s=='0')
   if (*++s) s++;
  while (*s) {
    i*=16;
    if (*s>='0' && *s<='9')
      i+=*s-'0';
      else if (*s>='a' && *s<='f')
            i+=*s-'a'+10;
            else if (*s>='A' && *s<='F')
                  i+=*s-'A'+10;
    s++;
  }
  return i;
}

main () {
  char s[10];
  printf("Input Hex Number: ");
  scanf("%s",s);
  printf("Result: %d\n",htoi(s));
  return 0;
}