实现strtol函数，其原型如为int strtol(con

#include<iostream>
using namespace std;

const int int_max = 2147483647;
const int int_min = -2147483648;

bool isAlph(char num)
{
	if ((num >= 'A'&& num <= 'Z') || (num >= 'a'&& num <= 'z'))
		return true;
	else
		return false;
}

bool isDigit(char num)
{
	if ((num >= '0'&& num <= '9'))
		return true;
	else
		return false;
}

char toLower(char num)
{
	char result = num;
	if (num >= 'A' && num <= 'Z')
		result += 32;
	return result;
}
int strtoLL(const char *num_str, char **endptr, int base)
{
	long long result = 0;
	long long value;
	if (!base)
	{
		if (*num_str == '0')
		{
			num_str++;
			if (*num_str == 'x' || *num_str == 'X')
			{
				base = 16;
				num_str++;
			}
			else
				base = 8;
		}
		else
			base = 10;
	}
	while (true)
	{
		if (isAlph(*num_str) || isDigit(*num_str))
		{
			value = isAlph(*num_str) ? toLower(*num_str) - 'a' + 10 : *num_str - '0';
			if (value >= base)
				break;
			result = result*base + value;
			if (result > int_max)
				result = int_max;	
			if (result < int_min)
				result = int_min;
			num_str++;
		}
		else
			break;
	}
	if (endptr)
		*endptr = const_cast<char*> (num_str);
	return result;
}

int Mystrtol(const char *num_str, char **endptr, int base)
{
	if (*num_str == '-')
	{
		 long result = strtoLL(num_str + 1, endptr, base);
		 if (result == int_max)
			 return int_min;
		 else
			 return -result;
	} 
	return strtoLL(num_str, endptr, base);
}

int main()
{
	char *str = "0123456789ABCDEFGHItest";
	char *temp;
	cout << "******Mystrtol********" << endl;
	int result = Mystrtol(str, &temp,0);
	cout << result << endl;
	cout << temp << endl;
	cout << "******strtol**********" << endl;
	result = strtol(str, &temp,0);
	cout << result << endl;
	cout << temp << endl;
	system("pause");
	return 0;
}