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【LeetCode】8. String to Integer (atoi)

题目:

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.

虽然是个简单题,但是要考虑的细节挺多的,比如输入空串的话如何输出,输入有+,-号的话怎么办,如果遇到无效输入怎么办?数字溢出了该如何输出?如果遇到的是面试,最好都要弄清楚。

 

class Solution {public:    int myAtoi(string str) {        if (str == "") return 0;        int flag = 1;        int res = 0;        string::const_iterator iter = str.begin();         while (*iter ==   && iter != str.end()) iter++;                if (*iter == + || *iter == -){            if (*iter == -) flag = -1;            *iter++;        }         while (iter!=str.end() && isValidNum(*iter)) {            int tmp = *iter - 0;            if (res > (INT_MAX - tmp) / 10 && flag == 1) return INT_MAX;            if (res > (INT_MAX - tmp) / 10 && flag == -1) return INT_MIN;                        res = res * 10 + tmp;            iter++;        }        return flag*res;    }        bool isValidNum(char c)    {        return c >= 0 && c <=9;    }};

 

【LeetCode】8. String to Integer (atoi)