memory content not erased after deleting my pointer (on a simple example)

Question

Here is a simple of example of a question I have: I create a pointer of integer (value 5), I print the pointer (hence the address) of the memory case it points to, as well as its content (5).

Then I delete that pointer, which is supposed to delete the content in the memory case that has the address of the pointer. But then when I print a and its content, as expected the address still exists. Nevertheless the content remains the same (5) as if a was not deleted... could you explain me? :-)

#include <iostream>
int main()
{
    int * a = new int(5);
    std::cout<< a << std::endl;
    std::cout<< "--------" << std::endl;
    delete a;
    std::cout<< a << std::endl;
    std::cout<< *a << std::endl;

    // end of my main
    return 0;
}

result:

0x7fff28403a90
--------  
0x7fff28403a90
5

_"Then I delete that pointer, which is supposed to delete the content in the memory case that has the address of the pointer."_ Where did you hear that? — Lightness Races in Orbit, Jun 15 '15 at 01:01
This famous Q&A is not a direct duplicate but is the perfect answer for just the same reason. I'm therefore biting the bullet and picking it as a duplicate. — Lightness Races in Orbit, Jun 15 '15 at 01:01

score 0 · Accepted Answer · answered Jun 15 '15 at 01:02

0

It may or may not print the same value after delete operation. So simply what you are observing is an undefined behavior.

answered Jun 15 '15 at 01:02

Steephen

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Thanks a lot! I see, when it frees the memory it does not replace the content by something else but in fact it keeps the content, but someone can write into that address anytime. – Aurélie JEAN Jun 16 '15 at 01:41
undefined behavior does not mean it should crash; What it means you will get non-deterministic result. – Steephen Jun 16 '15 at 01:43
I see, thanks Steephen! – Aurélie JEAN Jun 16 '15 at 01:46

memory content not erased after deleting my pointer (on a simple example)

1 Answers1