C++中的初始化与赋值

永远不要对一个未被初始化的存储区执行用户自定义的赋值操作，且看：

 1 #include <stdio.h>
 2 #include <string.h>
 3 
 4  class String{
 5 public:
 6     String(const char *init){
 7         if(!init) init = "";
 8         s_ = new char[strlen(init) + 1];
 9         strcpy(s_,init);
10     }
11     ~String(){
12         delete [] s_;
13     }
14     String &operator=(const char *str){
15         if(!str) str = "";
16         char *tmp = strcpy(new char[strlen(str) + 1],str);
17         if(!s_)
18             printf("s_ is NULL, you cannot delete it!\r\n");
19         delete [] s_;
20         s_ = tmp;
21         return *this;
22     }
23 private:
24     char *s_;
25 };
26 int main(int argc, char **argv)
27 {
28     String *names = static_cast<String *>(::operator new(100));
29     names[0] = "Sakamoto";
30      // it is very likely that you get a weird output!
31     printf("The value of names is :%s\n",names);
32     return 0;
33 }

posted on 2011-05-24 11:47  Joshua Leung  阅读(334)  评论(0)  编辑  收藏  举报

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