1 /* improvement on dealing with overflow accroding to this:
2 * https://discuss.leetcode.com/topic/57452/c-solution-beats-100
3 *
4 * be careful about the INT_MAX and INT_MIN
5 * this atoi is not thinking about special char like dot and so on.
6 */
7
8 class Solution {
9 public:
10 int myAtoi(string str) {
11 int i,nega_sign=1;
12 long long int re=0; //long long re to avoid overflow
13 for(i=0;i<str.size();i++) //skip to all the blank in the front of the string
14 {
15 if(str[i]!=' ')break;
16 }
17 if(str[i]=='+')i++; // deal with signature
18 else if(str[i]=='-'){ nega_sign=-1;i++;}
19 while(i<str.size()&&isdigit(str[i]))
20 /*when the string is over or the current char is not a valid integral number,no more conversion will be performed.
21 */
22 {
23 re=re*10+str[i]-'0';
24 if(nega_sign==-1&& -1*re<=INT_MIN)return INT_MIN; //overflow
25 else if (nega_sign==1&&re>=INT_MAX)return INT_MAX;
26 i++;
27 }
28 return re*nega_sign;
29 }
30 };
