Leetcode: String to Integer (atoi)-蒲公英云

Leetcode: String to Integer (atoi)

女爷i 2022-08-06 15:15 81阅读 0赞

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.

参考代码：

#define INT_MAX 2147483647
#define INT_MIN (-INT_MAX-1)
class Solution 
{
public:
    int atoi(const char *str)
    {
        if (str == nullptr)
        {
            return 0;
        }
        int position = 0;
        while (str[position] == ' ')
        {
            position++;
        }
        if (str[position] == '\0')
        {
            return 0;
        }
        int signal = 1;
        if (str[position] == '+' || str[position] == '-')
        {
            if (str[position] == '-')
            {
                signal = -1;
            }
            position++;
        }
        long long result = 0;// 注意这里是long long
        while (str[position] >= '0' && str[position] <= '9')
        {
            result = result * 10 + str[position] - '0';
            if (result * signal > INT_MAX)
            {
                return INT_MAX;
            }
            if (result * signal < INT_MIN)
            {
                return INT_MIN;
            }
            position++;
        }
        return result * signal;
    }
};