8. String to Integer (atoi)

class Solution {public:    int myAtoi(string str) {        int i = 0, c = 0;        double sum = 0;        if(str.size() == 0)        return 0;        if(str[0] == '+' || str[0] == '-' || str[0] == ' ' || (str[0] >= '0' && str[0] <= '9'))        {            while(str[i] == ' ')            i++;            if(str[i] == '+')            i++;            else if(str[i] == '-')            {                i++;                c = 1;            }            for(; i < str.size(); i++)            {            if(str[i] < '0' || str[i] > '9')            break;            sum = sum*10 + str[i]-'0';            if(c == 0 && sum >= INT_MAX)            return INT_MAX;            if(c == 1 && sum-1 >= INT_MAX)            return INT_MIN;            }            if(c == 1)            sum = -sum;        }        else        return 0;        return sum;    }};