亚马逊20120915网上机试第一题：atoi函数

#include <iostream>

using namespace std;
int toInteger(char string[]);
int main(){
    char string[100]={0};
    cin>>string;
    cout<<toInteger(string)<<endl;
    return 0;
}

int toInteger(char string[])
{
    //Your code is here
    int ret = 0;
    bool flag = true;
    unsigned int idx = 0;

    char c = string[idx];
    if (c == '+') {
        flag = true;
        ++idx;
    } else if (c == '-') {
        flag = false;
        ++idx;
    }

    for (; (c=*(string + idx)) != '\0' && c >= '0' && c <= '9'; ++idx) {
        if (flag) {
            int temp = ret * 10 + c - '0';
            if (ret >= temp) {
                return 2147483647;
            }
            else {ret = ret * 10 + c - '0';}
        }
        else {
            int temp = ret * 10 + c - '0';
            if (ret >= temp) {
                return -2147483648;
            }
            else {ret = ret * 10 + c - '0';}
        }

    }
    return flag ? ret : -ret;
}