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

int getdigit(char ch, int base)
{
	if (isdigit(ch)) ch-= '0';
    	else
    if (isalpha(ch) && ch <= 'Z') ch = 10 + ch - 'A';
       	else
    if (isalpha(ch)) ch = 10 + ch - 'a';
    	else 
    return -1;	
   	
   	if (ch / base != 0) return -1;	

   	return ch;
}


long int strtol (const char* str, char** endptr, int base)
{
    long int res = 0;
	int		sign = 1;

	if (base > 36)
	{
		errno = EINVAL;
	 	goto bye;
	}

	while (isspace(*str)) str++;

	if (*str == '-') { sign = -1; str++; }
		else
	if (*str == '+') str++;

	if (base == 0 || base == 16)
	{
		if (*str == '0' && (str[1] == 'x' || str[1] == 'X'))
		{
			base = 16;
			str += 2;
		}
	}

	if (base == 0 && *str == '0') base = 8;

	if (base == 0) base = 10;


	int digit;
	while ((digit = getdigit(*str, base)) >= 0)
	{
		res = base * res + digit;
		str++;
		if (res < 0)
		{
			errno = ERANGE;
			if (sign > 0)
				res = LONG_MAX;
			else
				res = LONG_MIN;
		}
	}

bye:
	if (endptr)
		*endptr = (char*)str;

	return res * sign;
}