The difference between delete and delete[] in C++ [duplicate]

Answer 1

• If you allocate with malloc(), you use free()
• If you allocate with new you use delete
• If you allocate with new[] you use delete[]
• If you construct with placement-new you call the destructor direct
• If it makes sense to use vector rather than new[] then use it
• If it makes sense to use smart-pointers then use them and don't bother to call delete (but you'll still need to call new). The matching delete will be in the smart-pointer.

https://isocpp.org/wiki/faq/freestore-mgmt

Answer 2

When we want to free a memory allocated to a pointer to an object then "delete" is used.

int * p;
p=new int;

// now to free the memory 
delete p;

But when we have allocated memory for array of objects like

int * p= new int[10]; //pointer to an array of 10 integer

then to free memory equal to 10 integers:

 delete []p;

NOTE: One can free the memory even by delete p;, but it will free only the first element memory.

Answer 3

And now it works fine.

More by luck that judgement if it does, and are you certain that it is really working?

The destructor for every object must be called, the delete[] operator uses information set by new[] to determine how many objects to destroy. So while delete on its own may recover the memory (though whether it does or not is implementation dependent), it may not call the destructor for each object allocated.

It is possible for the information about how the object's were allocated to be included when new or new[] are called so that the correct form of deletion is used regardless, but again that is implementation dependent and not guaranteed.