c++ - 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 stored? Is it standardised?

Answer 1

When you allocate memory on the heap, your allocator will keep track of how much memory you have allocated. This is usually stored in a "head" segment just before the memory that you get allocated. That way when it's time to free the memory, the de-allocator knows exactly how much memory to free.