leetcode--008. String to Integer (atoi)

题解

[-2147483648, 2147483647]

INT_MAX

INT_MIN

class Solution {
public:
int myAtoi(string str) {
if(str.empty()) return 0;

bool isNegative = false;
int i = 0, j = 0;
while(str[j] == ' ') j++;

i = j;
if(str[j] == '-') isNegative = true, i = j + 1;
if(str[j] == '+') i = j + 1;

long long num = 0;
for(; i < str.length(); ++i){
if(isdigit(str[i])) {
num = num * 10 + (str[i] - '0');
if(num > INT_MAX) return isNegative ? INT_MIN : INT_MAX;
}
else break;
}
return isNegative ? -num : num;
}
};