#include <stdio.h>
#include <stdlib.h>

int main()
{
   char str[30] = "0128912";
   char *ptr;
   long ret;
   
   ret = strtol(str, &ptr, 0);
   printf("Input: %s\n",str);
   printf("Result is %ld\n", ret);
   if (*ptr != '\0')        
        printf("Discarded: %s\n", ptr);
   return(0);
}

Input: 0128912
Result is 10
Discarded: 8912