C++ .reset()

The .reset() method is used with smart pointers in C++ (such as std::unique_ptr and std::shared_ptr). It releases ownership of the currently managed object (deleting it if this is the last owner) and optionally takes ownership of a new object passed as a raw pointer.

This method safely manages dynamic memory by deleting the previously managed object (if any), thereby helping to prevent memory leaks.

Syntax

ptr.reset();              // Releases ownership and deletes the managed object
ptr.reset(raw_ptr);       // Releases current object and takes ownership of raw_ptr

Example

This example demonstrates how .reset() releases ownership of the managed object, deletes it, and sets the pointer to null:

#include <iostream>
#include <memory>

int main() {
  std::unique_ptr<int> ptr(new int(42));
  std::cout << "Value before reset: " << *ptr << std::endl;

  ptr.reset(); // Releases ownership and deletes the managed object

  if (!ptr) {
    std::cout << "Pointer is null after reset." << std::endl;
  }
  return 0;
}

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The output of this code is:

Value before reset: 42
Pointer is null after reset.

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In this example:

• A std::unique_ptr manages an int with a value of 42.
• After calling .reset(), the managed object is deleted and the pointer becomes null.
• The check if (!ptr) confirms the pointer was successfully reset.

Codebyte Example

Run the following example to understand how the .reset() method works:

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