myatoi

#include <stdio.h>
#include <string.h>
#include <limits.h>

int myAtoi(char* str)
{
	long num = 0;
	int tag = 1;
	const int n = strlen(str);
	int i = 0;

	while(str[i]==' ' && i < n) i++;
	if(str[i] == '+') i++;
	if(str[i] == '-') {i++; tag = -1;}

	for(; i < n; i++) {
		if(str[i] < '0' || str[i] > '9') break;
		if(num > INT_MAX || num < INT_MIN)
			return tag == 1? INT_MAX : INT_MIN;
		num = num * 10 + str[i] - '0';
	}
	return (int)num * tag;
}

int main()
{
	char str[] = "++1";
	printf("%d\n", myAtoi(str));
	return 0;
}
#include <iostream>
#include <string>
#include <limits.h>

using namespace std;

class Solution {
public:
	int myAtoi(string str) {
		if(str.empty()) return 0;

		int len = str.length();
		long value = 0;
		int tag, i = 0;

		while(i < len && str.at(i) == ' ') i++;
		if(i == len)
			return 0;
		else if(str.at(i) == '-') {
			tag = -1;
			i++;
		} else if(str.at(i) == '+') {
			i++;
		}

		while(i < len) {
			if(str.at(i) < '0' || str.at(i) > '9') return int(value);

			value = value * 10 + tag * (str.at(i) - '0');
			if(value > INT_MAX) return INT_MAX;
			else if(value < INT_MIN) return INT_MIN;
			i++;
		}
		return (int)value;
	}
};

int main()
{
	Solution a;
	cout << a.myAtoi("-33.5a") << endl;
	return 0;
}