leetcode 8. String to Integer (atoi)

最新推荐文章于 2020-04-04 20:44:24 发布

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本文详细解析了如何将一个字符串转换为整数的过程，并提供了具体的实现代码。文章讨论了多种可能的输入情况，包括空字符串、非法字符串以及处理正负号等问题。

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.

Update (2015-02-10):
The signature of the C++ function had been updated. If you still see your function signature accepts a const char * argument, please click the reload button to reset your code definition.

解：主要需要考虑几种情况：空字符串，非法字符串，正号负号、overflow。

代码：

class Solution {
public:
    int myAtoi(string str) {
        int sign = 1, base = 0, i = 0;
        while(str[i] == ' ') ++i;
        if(str[i] == '+' || str[i] == '-'){
            sign = (str[i++] == '-')?-1:1;
        }
        while(str[i] >= '0' && str[i] <= '9'){
            if(base > INT_MAX/10 || (base == INT_MAX/10 && str[i] - '0' > 7)){
                return (sign == 1)?INT_MAX:INT_MIN;
            }
            base = 10*base + (str[i++] - '0');
        }
        return base*sign;
    }
};