Home > Backend Development > C++ > body text

Should Pointers Be Set to NULL in Destructors? A Look at Best Practices and Debugging.

Patricia Arquette
Release: 2024-10-28 06:30:30
Original
1055 people have browsed it

 Should Pointers Be Set to NULL in Destructors? A Look at Best Practices and Debugging.

Setting Pointers to NULL in a Destructor

In object-oriented programming, it's common to allocate memory dynamically and release it using destructors. Consider the following class that allocates memory for an object of type Bar:

<code class="cpp">class Foo
{
public:
  Foo() : bar(new Bar)
  {
  }

  ~Foo()
  {
    delete bar;
  }

  void doSomething()
  {
    bar->doSomething();
  }

private:
  Bar* bar;
};</code>
Copy after login

The question arises: is it beneficial to set the bar pointer to NULL in the destructor?

Argument against Setting to NULL

Contrary to popular belief, setting pointers to NULL in the destructor is not recommended. While it may seem like a good idea for debugging purposes, it could potentially lead to hidden problems in release builds.

If the pointer is set to NULL, a dangling reference to the deleted object might exist somewhere. In a debug build, this reference would be detected and trigger a diagnosable crash. However, in a release build, the buggy code might avoid using the pointer because it notices that it's NULL, thus obscuring the underlying issue.

Alternative Approach

Instead of setting the pointer to NULL, a better practice is to set it to a known bad pointer value. This way, any dangling references to the deleted object will still attempt to use the pointer, triggering a crash that can be more easily diagnosed and fixed.

For example, the following idiom could be used:

<code class="cpp">~Foo()
{
    delete bar;
    if (DEBUG) bar = (bar_type*)(long_ptr)(0xDEADBEEF);
}</code>
Copy after login

This approach allows potential bugs to be caught in debug builds while still ensuring that release builds detect and crash on dangling references.

Conclusion

While it might seem like a good idea to set pointers to NULL in destructors, doing so can hide potential issues in release builds. Instead, it's recommended to set pointers to a known bad value in debugging mode to facilitate diagnosis and debugging.

The above is the detailed content of Should Pointers Be Set to NULL in Destructors? A Look at Best Practices and Debugging.. For more information, please follow other related articles on the PHP Chinese website!

source:php.cn
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Latest Articles by Author
Popular Tutorials
More>
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template