C++程序设计
#ifndef STRING_H
#define STRING_H
#include <iostream.h>
class String
{
friend ostream & operator<<(ostream &,const String &);

public:
String(const char * ="1");
const String & operator=(const String &);
private:
int length;
char *sptr;
};
#endif



#include <string.h>
#include <iomanip.h>
#include <cstdlib>
#include "String.h"
String::String( const char *ptr)
:length(strlen(ptr)==0?strlen(ptr):0)
{
cout<<"Conversation constructor:"<<ptr<<endl;
sptr=new char [length+1];
strcpy(sptr,ptr);
}
const String & String::operator=(const String & string)
{
cout<<"operator=called"<<endl;
if (&string!=this)
{
delete [] sptr;
length=string.length;
sptr=new char [length];
strcpy(sptr,string.sptr);
}
else
cout<<"Attempted assigment of a string to itself."<<endl;
return *this;
}
ostream & operator<<(ostream & output,const String & string)
{
output<<string.sptr;
return output;
}





#include <iostream.h>
#include "String.h"
int main()
{
String str1("happy");
String str2(" birthday");
String str3;
cout<<"Str1 is \""<<str1<<"\";str2 is \""<<str2<<"\";str3 is \""<<str3<<'\"'<<"\n\nThe result of camparing str2 and str1 is:";
cout<<"\n\nTesting !str3:"<<endl;
cout<<"str3 is empty;assigning str1 to str3:"<<endl;
str3=str1;
cout<<"str3 is \""<<str3<<'\"';
return 0;
}



这个程序中，重载的=运算符函数中，为什么使用了delete后，运行程序总是弹出对话框终止程序。

[解决办法]

C/C++ code

sptr=new char [length];
[解决办法]
嗯嗯，楼上正解。