_DEBUG vs. NDEBUG: Which Preprocessor Define is Best for Debugging Code?

_DEBUG vs NDEBUG: Preprocessor Defines for Debug Sections of Code

When writing code that has sections that should only be active during debugging, it becomes important to have a way to conditionally include or exclude these sections. In C/C , this is achieved using preprocessor directives like #ifdef and #ifndef.

Which preprocessor define is recommended for debug sections?

There are two commonly used preprocessor defines for this purpose:

• _DEBUG: This define is specific to Microsoft Visual Studio and is set when the /MTd or /MDd options are used.
• NDEBUG: This define is part of the C standard library and is intended to disable standard-C assertions.

How should these defines be used?

#ifdef _DEBUG
    // Debugging code here
#endif

#ifndef NDEBUG
    // Debugging code here
#endif

Advantages and Disadvantages

• _DEBUG: Consistent with MS CRT debugging techniques, but not standard.
• NDEBUG: Consistent with assert() and standard-C assertions, but may be ignored by some debuggers.

Alternative Approach

If you want to avoid using preprocessor defines provided by the compiler or standard library, you can create your own debugging macro with a unique name, as long as it doesn't start with an underscore.

Conclusion

Whether to use _DEBUG or NDEBUG depends on the specific needs of your project and the debugging tools being used. However, it is generally recommended to use NDEBUG for portability and consistency with standard assertions.

The above is the detailed content of _DEBUG vs. NDEBUG: Which Preprocessor Define is Best for Debugging Code?. For more information, please follow other related articles on the PHP Chinese website!