LeetCode 8: String to Integer(atoi)

LeetCode String

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.

代码

C语言版本：

int myAtoi(char* str) {
    int sign = 1;
    int res = 0;
    if (!str) {
        return str;
    }
    while(' ' == *str) {
        str++;
    }
    if ('-' == *str || '+' == *str) {
        sign = *str++ == '+' ? 1 : -1;
    }
    while(*str >= '0' && *str <= '9') {
	if (res > INT_MAX / 10 || (res == INT_MAX / 10 && *str - '0' > 7)) {
		return sign > 0 ? INT_MAX : INT_MIN;
	}
	res = res * 10 + (((int)*str++) - '0');
    }
    return res * sign;
}

1047 / 1047 test cases passed.
Status: Accepted
Runtime: 4 ms