[LeetCode] 8. String to Integer (atoi)

int myAtoi(string str) {
long long res = 0;
int sign = 1, i = 0;

while (str[i] = ' ') i++;

if (str[i] == '+') i++;
else if (str[i] == '-') i++, sign = -1;

for (; i < str.length(); i++) {
if (str[i] >= '0' && str[i] <= '9') {
res = res * 10 + str[i] - '0';
if (res > INT_MAX)
return sign > 0 ? INT_MAX : INT_MIN;
}
else break;
}

res = (int)(res * sign);
return res;
}