How to Globally Replace Standard Memory Allocation with Custom Implementations in C ?

How to Globally Replace Standard Memory Allocation with Custom Implementations

Despite previous discussions on Stack Overflow, you may encounter challenges in globally overriding the new and delete operators with custom implementations. This article provides a revised solution that effectively replaces the standard operators and ensures consistent use of your custom memory manager throughout your codebase.

To achieve this global replacement, you need to create a separate translation unit (TU) that defines these operators. Here's an example:

<code class="cpp">// optional_ops.cpp

void * operator new(std::size_t n) throw(std::bad_alloc)
{
  // ... Your custom memory allocation logic here
}

void operator delete(void * p) throw()
{
  // ... Your custom memory deallocation logic here
}</code>

Unlike regular functions, the declarations for operator new and operator delete are implicitly defined in the language. Therefore, you don't need separate header files to declare them. However, since you use STL, you'll likely need to include headers like or to provide definitions for std, std::bad_alloc, and std::size_t.

C 11 and Beyond Enhancements

In C 11 and later, you have additional options for defining these operators:

• decltype(sizeof(0)): Instead of using std::size_t, you can use this alternative syntax to get the size of the first parameter without relying on external libraries.
• noexcept(false): This syntax replaces the outdated dynamic exception specification and indicates that the operator can throw exceptions.

Here's an example of an updated operator new definition using these enhancements:

<code class="cpp">void * operator new(decltype(sizeof(0)) n) noexcept(false)
{
  // ... Your custom memory allocation logic here
}</code>

By linking the TU containing your custom operator definitions into your codebase, you can replace the standard new and delete operators globally. This ensures that all memory allocation and deallocation calls use your custom implementations, resolving your concerns about mixed operator usage in STL and other libraries.

The above is the detailed content of How to Globally Replace Standard Memory Allocation with Custom Implementations in C ?. For more information, please follow other related articles on the PHP Chinese website!