Have macro 'return' a value

Question

I'm using a macro and I think it works fine -

 #define CStrNullLastNL(str) {char* nl=strrchr(str,'\n'); if(nl){*nl=0;}} 

So it works to zero out the last newline in a string, really its used to chop off the linebreak when it gets left on by fgets.

So, I'm wondering if I can "return" a value from the macro, so it can be called like

 func( CStrNullLastNL( cstr ) ) ; 

Or will I have to write a function

Answer 1

For a macro to "return a value", the macro itself has to be an expression. Your macro is a statement block, which cannot evaluate to an expression.

You really ought to write an inline function. It will be just as fast and far more maintainable.

Answer 2

#define CStrNullLastNL(str) ({ \     char* nl=strrchr(str,'\n');\     if(nl){*nl=0;} \     nl; \ }) 

should work.

Edit: ... in GCC.