1 class Solution {
2 public:
3 int atoi(const char *str) {
4 while (*str==' ')
5 str++;
6 int sign = 1;
7 if (*str=='+')
8 str++;
9 else if (*str=='-'){
10 str++;
11 sign = -1;
12 }
13 unsigned rlt=0;
14 unsigned maxL = INT_MAX;
15 if (sign==-1)
16 maxL += 1;
17 while (*str<='9' && *str>='0'){
18 unsigned int off = *str-'0';
19 unsigned int t = maxL - off;
20 if (t/10 < rlt){
21 if (sign==1)
22 return INT_MAX;
23 return INT_MIN;
24 }
25 rlt = rlt * 10 + off;
26 str++;
27 }
28 if (sign==1)
29 return rlt;
30 return (-1) * rlt;
31 }
32 };
