Is assert(false) ignored in release mode?

Question

I am using VC++. Is assert(false) ignored in release mode?

Answer 1

If compiling in release mode includes defining NDEBUG, then yes.

See assert (CRT)

Answer 2

IIRC, assert(x) is a macro that evaluates to nothing when NDEBUG is defined, which is the standard for Release builds in Visual Studio.

Answer 3

The assert macro (at least it is typically a macro) is usually defined to no-op in release code. It will only trigger in debug code. Having said that. I have worked at places which defined their own assert macro, and it triggered in both debug and release mode.

I was taught to use asserts for condition which can "never" be false, such as the pre-conditions for a function.

Answer 4

Only if NDEBUG is defined I think (which it will be by default for Visual C++ apps).

Answer 5

I think it is a mistake to rely too much on the exact behavior of the assert. The correct semantics of "assert(expr)" are:

• The expression expr may or may not be evaluated.
• If expr is true, execution continues normally.
• If expr is false, what happens is undefined.

More at http://nedbatchelder.com/text/assert.html

Answer 6

same for GNU :

  #ifdef    NDEBUG

  # define assert(expr)     (__ASSERT_VOID_CAST (0))