leetcode 8 -- String to Integer (atoi)

** 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

Requirements for atoi:
The function first discards as many whitespace characters as necessary until
the first non-whitespace character is found. Then, starting from this
character, takes an optional initial plus or minus sign followed by as many
numerical digits as possible, and interprets them as a numerical value.

The string can contain additional characters after those that form the
integral number, which are ignored and have no effect on the behavior of this

If the first sequence of non-whitespace characters in str is not a valid
integral number, or if no such sequence exists because either str is empty or
it contains only whitespace characters, no conversion is performed.

If no valid conversion could be performed, a zero value is returned. If the
correct value is out of the range of representable values, INT_MAX
(2147483647) or INT_MIN (-2147483648) is returned.

** 题意 **

注意三个问题 :
数值越界问题 (题意已提到 若越界则输出INT-MAX 或 INT-MIN)

** 思路 **


** 代码 **

int myAtoi(char* str) {
    int i=0;
    long long rel;//考虑到越界问题用longlong保存
    while(str[i]==' '){i++;}
    rel=atol(str);//此处取巧了 用了atol
        return INT_MAX;
    else if(rel<INT_MIN)
        return INT_MIN;
    return rel;