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leetcode - String to Integer (atoi)

2013-12-16 20:46  张汉生  阅读(172)  评论(0)    收藏  举报

 

 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 };