Double delete of data doesn't crash

Question

I am trying to learn C++ and was writing programs to learn Copy Constructors and Operator overloading. I am surprised that the below program when Copy constructor is used do

Answer 1

I wirte this piece of test code, hope it will help here, I think crush is related to platform a lot, it is not just by chance, since this piece of code crush in linux ,but works fine in codeblock IDE

#include 
#include 
#include 
using namespace std;

class XHandler
{
    public:
    XHandler()
    {
            data = new char[8];
            strcpy(data, "NoName");
            std::cout<< "default construcor is called" << std::endl;
    }
    XHandler (const char *str)
    {
            data = new char [strlen(str) + 1 ];
            strcpy (data, str);
             std::cout<< "param construcor is called" << std::endl;

    }
    XHandler (const XHandler &xh)
    {
            data = xh.data;
            std::cout<< "copy construcor is called" << std::endl;

    }
    XHandler& operator = (const XHandler &xh)
    {
            data = xh.data;
            std::cout<< "operator construcor is called" << std::endl;

            return *this;
    }
    ~XHandler()
    {
        std::cout<< "destrucor is called" << std::endl;
        print_dir();
        if (data)
        {
            delete [] data;
            data = NULL;
            std::cout<< "delete data" << std::endl;
        }



    }
    void debug()
    {
            cout << data <

it crush in linux gcc4.1.2 ,it outputs

param construcor is called
param construcor is called
hello
there
location: 0x502010
location: 0x502030
copy construcor is called
location: 0x502010
hello
default construcor is called
operator construcor is called
hello
destrucor is called
location: 0x502010
delete data
destrucor is called
location: 0x502010
*** glibc detected *** ./test: double free or corruption (fasttop): 0x0000000000502010 ***