Is there a memory leak in this small program?

[MrProgrammer]

Sorry for asking so many pointer questions.. My last one though...

#include <iostream>
using namespace std;
class Box {
public:
    int x, y;
};

Box* eenNieuweBox() {
    Box b;
    b.x = 5;
    return &b;
}

int main() {
    Box* b;
    
    b = eenNieuweBox();
    cout<<b->x;
    return 0;
}

I assume if you don't use the new keyword, you don't have to delete it right? So this program is good?

[nkendra]

There isn't any memory leaks because no free store memory is allocating using new.

However, there is a huge problem with eenNieuweBox(). Box b is created on the stack of the eenNieuweBox() function call, which means b will be destroyed when the function returns. By returning a pointer to b, the function is returning a pointer to a destroyed object. Instead, return b by value.

Box eenNieuweBox() {
    Box b;
    b.x = 5;
    return b;
}

Never put user defined anyting in the std namespace.

[MikeyBoy]

Your program will crash exhibit undefined behaviour. Box b is created on the stack in your eenNieuweBox() function. When the function returns, b falls out of scope and the box is destroyed. In main, your pointer b will be pointing to memory that is no longer valid.

[vlad from moscow]

The program has undefined behaviour because you are returning a pointer to a local variable from a function. This local variable will be destroyed or can be overwritten by something else so the pointer will be invalid.
So there is no memory leak but there is undefined behaviour.

[MrProgrammer]

Thank you.