Why should we overload/override new and delete? [duplicate]

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Any reason to overload global new and delete?

Why should we overload/override new and delete in C++?

Give me an example of situation in which we should overload/override new, new[], delete or delete[].

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This sounds a bit like a homework assignment. Nevertheless, here are two uses off the top of my head:

• For profiling purposes. For instance, we use it in a library as a poor-man’s valgrind to track memory leaks.
• To implement a custom allocator (e.g. a pool allocator) for your objects. Usually I’d implement an allocator for this, though.

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To provide your implementation of allocating/deallocating memory. new/delete are very general. When you know how your application is going to use memory you can provide more efficient version of new/delete. That would be very simple for example if you used a lot of small object.

Another usage would be to provide memory leak detection.

That's not very often used mechanism - at least in my experience.