c++delphi

In C++, can I use a preprocessor directive inside of a statement on one line, like I can do in Delphi?

The C/C++ ternary operator is great:

int x = (someFlag) ? -1 : 1;

Delphi has a nice feature where preprocessor directives can be written on one line. Two examples:

x := {$IFDEF DBG_MY_SYMBOL} -1 {$ELSE} 1 {$ENDIF};
x := {$IF Defined(DBG_MY_SYMBOL)} -1 {$ELSEIF Defined(ANOTHER_SYMBOL)} 1 {$IFEND};

Beautiful!

Does C/C++ have a one-line equivalent like Delphi?

Solution

  • Does C/C++ have a one-line equivalent like Delphi?

    Unfortunately, no. A C/C++ preprocessor directive is takes up a whole line by itself, so there is no direct equivalent in C/C++ to your Delphi example.

    However, in C/C++, expressions can span multiple lines, so you can do something like this instead:

    x =
  #ifdef DBG_MY_SYMBOL
  -1
  #else
  1
  #endif
;

    Or:

    x = 
  #if defined(DBG_MY_SYMBOL)
  -1
  #elif defined(ANOTHER_SYMBOL)
  1
  #endif
;

    That being said, you should consider using a separate constant for better readability, eg:

    #ifdef DBG_MY_SYMBOL
const int MyConstant = -1;
#else
const int MyConstant = 1;
#endif

x = MyConstant;

    Or:

    #if defined(DBG_MY_SYMBOL)
const int MyConstant = -1;
#elif defined(ANOTHER_SYMBOL)
const int MyConstant = 1;
#endif

x = MyConstant;