Question

class A
{
    char *name;
public:
    A();
    A(char*);
    ~A();
};

A::A()
{

}
A::A(char* s)
{
    int k=strlen(s);
    name=new char[k+1];
    strcpy_s(name,k+1,s);
}
A::~A()
{
    if(name!=NULL)
        delete[] name;
}

int _tmain(int argc, _TCHAR* argv[])
{
    A *v=new A[20];
    delete[] v;
    system("pause");
    return 0;
}

I get the following error at runtime: Unhandled exception at 0x5B987508 (msvcr110d.dll) in test212.exe: 0xC0000005: Access violation reading location 0xCDCDCDC1.
It’s obviously a memory problem, but can you please tell me what happens in this example of code?

Answer 1

new A[20] calls the default constructor, and you don’t initialize name in the default constructor. You can’t assume that it will be set to NULL for you. In the absence of initialization, delete[] name has undefined behaviour.