#include <stdio.h>

// These are macro substitution so..

#define weeks(mins)	(days(mins)/7)		// How many weeks from so many days
#define days(mins)	(hours(mins)/24)	// How many days from so many hours
#define hours(mins)	(mins/60)			// How many hours from so many mins
#define mins(secs)	(secs/60)			// How many mins from so many secs
#define PRINT(a)	printf(#a " = %d\n",(int)(a))
#define TRACE(x)	if(traceon) printf("Trace: "), PRINT(x)

// this is the call to 'g' "g(oo,dbye)" oo is defined as "th"
// See "The C programming Language" by Kernighan, and Ritchie on the Preprocessor commands # and ##
// #undef will undefine a MACRO  ## concatenateactual arguments during MACRO expansion.
#define g(a,b)		a a ## b(nd)
#define oo			"th"
#define oodbye(a)	"e e" #a

int traceon;

main()
{
	{ // start nest
		PRINT( weeks(10080) ); // 10080 mins makes a week
		PRINT( days(mins(86400)) ) ; // 86400 secs make a day
	} // end nest


/******	
FEUER original code....

TRACE includes an open if statement.  
On expansion the if consumes the following else.
Thus the puts is called only when i<10 and !traceon
As traceon is set to 1 and not changed in the rest of the
for execution the else puts("not yet"); is never seen.

	{ // start nest
		int i;
		traceon = 1;
		for( i=20; i>0; i/=2 )	{
			if( i<10 ) TRACE(i);
			else puts("not yet");						
		} // end for
	} // end nest


THIS .....		
	if( i<10 ) TRACE(i);
	else puts("not yet");						
EXPANDS TO THIS....
	if( i<10 )
		if(traceon)
			printf("Trace: "), PRINT(x);
		else puts("not yet");
******/	
	
	
	{ // start nest
		int i;
		traceon = 1;
		for( i=20; i>0; i/=2 )	{
			if( i<10 ) {
				TRACE(i);
			}
			else {
				puts("not yet");			
			}
		} // end for
	} // end nest


/********	
The extra line between the 'if' and the 'else' trips this error
"error C2181: illegal else without matching if"

	{
int c = 1;
if(c<0) puts("c<0"); 
put("this is between the 'if' and the 'else'"); 
else puts("c>0");
	}
********/


	{ // start nest
		puts( g(oo,dbye) );
	} // end nest

}// end main