How to use operator new to count number of times of dynamic memory allocation

Yes, and here is how you could do it:

#include <new> #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <sstream> int number_of_allocs = 0; void* operator new(std::size_t size) throw(std::bad_alloc) { ++number_of_allocs; void *p = malloc(size); if(!p) throw std::bad_alloc(); return p; } void* operator new [](std::size_t size) throw(std::bad_alloc) { ++number_of_allocs; void *p = malloc(size); if(!p) throw std::bad_alloc(); return p; } void* operator new [](std::size_t size, const std::nothrow_t&) throw() { ++number_of_allocs; return malloc(size); } void* operator new (std::size_t size, const std::nothrow_t&) throw() { ++number_of_allocs; return malloc(size); } void operator delete(void* ptr) throw() { free(ptr); } void operator delete (void* ptr, const std::nothrow_t&) throw() { free(ptr); } void operator delete[](void* ptr) throw() { free(ptr); } void operator delete[](void* ptr, const std::nothrow_t&) throw() { free(ptr); } int main () { int start(number_of_allocs); // Your test code goes here: int i(7); std::ostringstream os; os<<i; std::string s=os.str(); // End of your test code int end(number_of_allocs); std::cout << "Number of Allocs: " << end-start << "\n"; } 

In my environment (Ubuntu 10.4.3, g++), the answer is "2".

The global operator new function is called when the new operator is used to allocate objects of built-in types, objects of class type that do not contain user-defined operator new functions, and arrays of any type. When the new operator is used to allocate objects of a class type where an operator new is defined, that class's operator new is called.

So every new-expression will invoke the global operator new, unless there is a class operator new. For the classes you listed, I believe that there is no class-level operator new.