[C ++] ndebug macro and Assert Behavior

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• Reference

 

1. The ndebug macro is a macro defined in standard C and is used to control assert () behavior. If this macro is defined, assert does not work.

# Ifdef ndebug
# Define assert (x) (void) 0)
# Else
...

2. In C standard, assert is implemented using macros. <Assert. h> it is designed to be included for multiple times. When it comes to UNDEF assert, The ndebug macro determines its behavior. For example:

# Ifdef ndebug
# UNDEF ndebug
# Include <assert. h>
# Define ndebug
# Else
# Include <assert. h>
# Endif // # ifdef ndebug

Replace the aboveCodePut it at the top of C/CPP (of course, no other # include <assert. h> statement) to ensure that the assert in the compilation unit where c/CPP is located will also trigger the abort action under release.

3. Ndebug macro is also used as a macro for judging the debug/release version due to its literal meaning. However, it is related to the compiler and environment and is not reliable.

For example, in VC, this macro is defined by default for the generated release version project, but GCC is not defined, and it must be defined using the-dndebug parameter.

4. C ++ standard fully uses the definition in C.

Reference

• C-approved standards
  Http://www.open-std.org/jtc1/sc22/wg14/www/standards.html#9899
• C ++ standard (ISO/IEC 14882)