std::reference_wrapper

std::reference_wrapper<T> is a lightweight, copyable object that stores a reference to a T. It allows you to treat a reference as if it were a regular assignable object.

Key Properties

• Wraps a reference (T&), not a pointer.
• Copyable and assignable, all copies refer to the same underlying object.
• Does not extend lifetime, the referenced object must outlive the reference_wrapper.
• Access the reference with .get() or implicit conversion to T&.

Example

#include <functional> // for std::reference_wrapper
#include <iostream>
 
int main()
{
	int x = 42;
	std::reference_wrapper<int> ref = std::ref(x);
 
	std::cout << "Value: " << ref.get() << std::endl; // Output: Value: 42
 
	ref.get() = 100; // Modify the original variable through the reference wrapper
	std::cout << "Modified Value: " << x << std::endl; // Output: Modified Value: 100
 
	return 0;
}