#ifdef DEBUG

This is a discussion on #ifdef DEBUG within the C++ Programming forums, part of the General Programming Boards category; Hi, I was wondering in what case the following code defining ASSERT will be processed by gcc : Code: #ifdef ...

  1. #1
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    #ifdef DEBUG

    Hi,
    I was wondering in what case the following code defining ASSERT will be processed by gcc :
    Code:
    #ifdef DEBUG
    #define ASSERT(x) if(!(x)) { \
      std::cerr << "ASSERT FAILED IN " << __FILE__ << ":" << __LINE__ << endl; \
      abort(); \
    }
    #else
    #define ASSERT(x)
    #endif
    Is it when specifying -g to gcc?

    Is ASSERT defined as such same as assert() in assert.h?

    Thanks!

  2. #2
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by lehe View Post
    Hi,
    I was wondering in what case the following code defining ASSERT will be processed by gcc :
    Whenever DEBUG is defined. gcc will never define it itself (even with -g). You must define it manually.

    The built-in assert will trigger by default, unless NDEBUG is defined. Again, the compiler DOES NOT DEFINE THIS FOR YOU. You must define it yourself when building for release.
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

  3. #3
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    I'm very much doubting that...
    Code:
    #include <stdio.h>
    
    int main()
    {
      #if DEBUG
      printf("Debug\n");
      #else
      printf("No Debug\n");
      #endif
      return 0;
    }
    compiled with gcc -g dbg.c, and then executing will show "No Debug" - at least using gcc-mingw 3.4.

    There is a symbol "NDEBUG" that is normally set by the compiler in "NO Debug" mode.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

  4. #4
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by matsp View Post
    There is a symbol "NDEBUG" that is normally set by the compiler in "NO Debug" mode.
    I didn't think the compiler ever did that itself. I want to be able to enable asserts in release mode, or disable them for a debug build, if I want. Why should the compiler prevent me?

    And anyway, "release" and "debug" are just conveniences -- all that's actually real are the set of compiler switches. The -g flag means symbolic debugging information, not "build for debug." I can ask for optimization and debug at the same time if I want..
    Code:
    //try
    //{
    	if (a) do { f( b); } while(1);
    	else   do { f(!b); } while(1);
    //}

  5. #5
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    Sorry, you are right, I'm wrong. I'm probably confusing this with the "regular build setup in Visual studio", which normally DOES set NDEBUG in the release mode.

    --
    Mats
    Compilers can produce warnings - make the compiler programmers happy: Use them!
    Please don't PM me for help - and no, I don't do help over instant messengers.

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