Question

I am not able to understand this behavior. I have a class A,

class A
{
public:
int ch;
char *s;
A()
{}
A(char *st):ch(0)
{
    s = new char[10];
    strcpy(s,st);

}
A(const A& rhs):ch(rhs.ch)
{
    s = new char[strlen(rhs.s)+1];
    strcpy(s,rhs.s);
}
const A& operator=(const A& rhs)
{
    char *temp = new char[strlen(rhs.s)+1];
    strcpy(temp,rhs.s);
    delete[] s;
    s=temp;
    ch = rhs.ch;
    return *this;
}
~A()
{
    delete []s;
}
};

Till this point everything goes as expected I am able to test my copy constructor and assignment operator and they are working properly.

Now I created a child class B and I am getting heap corruption error. I am not able to understand, is this the problem related somewhere with class A destructor. ?
Below is my class B,

class B:public A
{

public:
int a;
B():a(0){}
};

Answer 1

You default constructor for A does not initialise the member s (a pointer):

A()
{}

Hence when elements are constructed using this constructor, you get a crash when the destructor deletes the uninitialized element:

~A()
{
  delete []s;
}

Class B uses the default constructor for A, and therefore triggers this problem. Avoid it by properly initializing all members in the default constructor:

A() : ch(), s(0)
{ }