How does delete[] “know” the size of the operand array?

Question

Foo* set = new Foo[100];
// ...
delete [] set;

You don\'t pass the array\'s boundaries to delete[]. But where is that information stor

Answer 1

The information is not standardised. However in the platforms that I have worked on this information is stored in memory just before the first element. Therefore you could theoretically access it and inspect it, however it's not worth it.

Also this is why you must use delete [] when you allocated memory with new [], as the array version of delete knows that (and where) it needs to look to free the right amount of memory - and call the appropriate number of destructors for the objects.