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Function Names as Strings Contents|Index|Previous|Next
 Function names as strings   

GNU CC predefines two string variables to be the name of the current function. The variable, __FUNCTION__, is the name of the function as it appears in the source. The variable, __PRETTY_FUNCTION__, is the name of the function pretty printed in a language specific fashion. These names are always the same in a C function, but in a C++ function they may be different, like the following program.
    extern "C" { 
    extern int printf (char *, ...); 
    } 
    class a { 
    public: 
      sub (int i) 
        { 
         printf ("__FUNCTION__ = %s\n", __FUNCTION__); 
         printf ("__PRETTY_FUNCTION__ = %s\n", __PRETTY_FUNCTION__); 
        } 
    }; 
    int 
    main (void) 
    { 
      a ax; 
      ax.sub (0); 
      return 0; 
    }
The program, then, gives the following output.
    __FUNCTION__ = sub 
    __PRETTY_FUNCTION__ = int a::sub (int)
These names are not macros: they are predefined string variables. For example, #ifdef __FUNCTION__ does not have any special meaning inside a function, since the preprocessor does not do anything special with the identifier, __FUNCTION__.

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