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c++delete-operator

C++ delete[] operator confusion

I am studying pointers atm. and I got confused with delete[] operator. Here is an example:

int* a = new int[12];

for (int i=0; i<12; i++)
    a[i]=123;

delete[] a;

for (int i=0; i<12; i++)
  cout <<a[i]<<" ";

If I got it correctly, delete[] operator should destory all objects in an array. But my output is this:

10621288 10617028 123 123 123 123 123 123 123 123 123 123

Only first two elements are destroyed. Have I made something wrong?

Solution

  • What you have done wrong is trying to access the contents of a after it has been deleted. This invokes undefined behavior (UB), which means "anything goes". You must never do that, it is a crash-worthy bug in the code.

    The results you see are simply one particular specialization of "anything". Running this program on another system, or using a different compiler, or using the same compiler with different settings, is likely to end up doing something else.