Help with macros

This is a discussion on Help with macros within the C Programming forums, part of the General Programming Boards category; I need help because what I want, I dont know if it is possible to do it with macros. I ...

  1. #1
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    Feb 2008
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    Help with macros

    I need help because what I want, I dont know if it is possible to do it with macros.

    I have:
    Code:
    #ifdef ESTADISTICAS
    #   define   S(x)  (x)
    #else
    #   define   S(x)
    #endif
    It is a macro to allow me to collect stats. Now I do something like:
    Code:
    S(++stats.cortes);
    But when I want something more complex like:
    Code:
    #ifdef ESTADISTICAS
    if (cont < 3) ++stats.move_hit[cont];
    #endif
    It takes me three lines of code. Is there any way to do it in a only one line? like:
    Code:
    S(if (cont < 3) ++stats.move_hit[cont]);
    Doing this way would allow me a more friendly code and more readable, in a single line, but when I compile I get an error "expected expression berore if".

  2. #2
    and the hat of wrongness Salem's Avatar
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    It you want complicated things to appear as single statements, then perhaps this.
    Code:
    #ifdef ESTADISTICAS
    #   define   S(x)  do { \
        x                   \
        } while(0)
    #else
    #   define   S(x)
    #endif 
     
    int
    main(void)
    {
      struct {
        int move_hit[3];
      } stats;
      int cont = 0;
      S(if (cont < 3) ++stats.move_hit[cont];);
      return 0;
    }
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  3. #3
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    Quote Originally Posted by Salem View Post
    It you want complicated things to appear as single statements, then perhaps this.
    Code:
    #ifdef ESTADISTICAS
    #   define   S(x)  do { \
        x                   \
        } while(0)
    #else
    #   define   S(x)
    #endif 
     
    int
    main(void)
    {
      struct {
        int move_hit[3];
      } stats;
      int cont = 0;
      S(if (cont < 3) ++stats.move_hit[cont];);
      return 0;
    }
    Thanks, it works perfect.

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