atol实现【转】

 1 int my_atoi(const char *str)  
 2 {  
 3     assert(str != NULL);  
 4     int flag = 1;  
 5     int result = 0;  
 6     while(*str == ' ' || *str == '\n' || *str == '\t')  
 7     {  
 8         ++str;  
 9     }  
10     if(*str == '-')  
11     {  
12         flag = -1;  
13         ++str;  
14     }  
15     else if(*str == '+')  
16     {  
17         ++str;  
18     }  
19     while(*str != '\0')  
20     {  
21         if(*str >= '0' && *str <= '9')  
22         {  
23             result = result*10 + *str - '0';  
24         }  
25         else  
26         {  
27             return flag * result;  
28         }  
29         ++str;  
30     }  
31     return flag * result;  
32 }  

 

转载于:https://www.cnblogs.com/zzb-Dream-90Time/p/6829452.html