folllowing code should call the copy constructor and shud not give run time error!

[Alexpo]

#include "stdafx.h"
#include <iostream>
using namespace std;

class MyString
{
public: 
	
	MyString(const char *str="")
	{
		length = strlen(str);
		name = new char[length + 1];
		strcpy(name,str);
	};
	
	//copy constructor
	MyString(const MyString& o)
	{
		length=o.length;
		name = new char[length+1];
		strcpy(name,o.name);
	};
	
	//desctructor
	~MyString()
	{
		delete name;

	};
	void display()
	{
		cout<<"name: " << name << endl;
	}
private:
	char *name;
	int length;
};

int _tmain(int argc, _TCHAR* argv[])
{
	
	MyString* obj = new MyString("alex");
	MyString* obj2=obj; 
	
	delete obj; // this line deleting the "name" in obj2. but it shud not.what is wrong       //in     my understanding.
	obj2->display();

	return 0;
}

[anon]

It shouldn't.

You are not copying MyString instances, you are assigning pointers. Both pointers point to the same instance which you delete before accessing it through the other pointer.

What you should be doing:

int main()
{

	MyString obj("alex");
	MyString obj2(obj);

	obj2.display();

	return 0;
}

Note that you also need to overload the assignment operator to perform "deep copy-assignment".

[Alexpo]

Thanks Anon,

exactly....obj and obj2 are pointers not instances of MyString.
how stupid sometime a person can get.

[hk_mp5kpdw]

MyString(const char *str="")
{
	length = strlen(str);
	name = new char[length + 1];
	strcpy(name,str);
};
	
//copy constructor
MyString(const MyString& o)
{
	length=o.length;
	name = new char[length+1];
	strcpy(name,o.name);
};
	
//desctructor
~MyString()
{
	delete name;
};

You can get rid of those semicolons at the end of the functions... and your destructor needs to be

~MyString()
{
	delete [] name;
}