刷LeetCode（8）——String to Integer (atoi)

Code it now! https://leetcode.com/problems/string-to-integer-atoi/description/

Implement atoi to convert a string to an integer.

Hint:

Carefully consider all possible input cases. If you want a challenge, please do not see below and ask yourself what are the possible input cases.

Notes:

It is intended for this problem to be specified vaguely (ie, no given input specs). You are responsible to gather all the input requirements up front.

实现如下：这题也比较好做，关键是要考虑挺多东西，我也是提交了好多次才发现有这么多要考虑的地方
如下：

开头的空格

正负符号的处理

溢出处理

非法输入

#include <iostream>#include <string>#include <limits.h> #include <assert.h>using namespace std;class Solution {public:    int myAtoi(string& str) {        int i = 0,sign = 1;        long long ret = 0;        const int len = str.length();        if( !len )        {            return 0;        }        while( i < len && isspace( str.at(i) ) )        {            i++;        }        while( i < len )        {            if( str.at(i) == '+' )            {                i++;                sign = 1;                continue;            }            if( str.at(i) == '-' )            {                i++;                sign = -1;                continue;            }            if( str.at(i) < '0' || str.at(i) > '9' )            {                return 0;            }            ret = ret*10 + sign*(str.at(i++) - '0');        }        if( ret > INT_MAX || ret < INT_MIN ){            return 0;        }        return ret;     }};int main(){    string str;    while( getline(cin,str) && !str.empty() )    {        cout << Solution().myAtoi(str) << endl;    }    return 0;}