How do you create a debug only function that takes a variable argument list? Like printf()

Question

I\'d like to make a debug logging function with the same parameters as printf. But one that can be removed by the pre-processor during optimized builds.

<

Answer 1

This is how I do debug print outs in C++. Define 'dout' (debug out) like this:

#ifdef DEBUG
#define dout cout
#else
#define dout 0 && cout
#endif

In the code I use 'dout' just like 'cout'.

dout << "in foobar with x= " << x << " and y= " << y << '\n';

If the preprocessor replaces 'dout' with '0 && cout' note that << has higher precedence than && and short-circuit evaluation of && makes the whole line evaluate to 0. Since the 0 is not used the compiler generates no code at all for that line.