#include <stdio.h>
#include <stdarg.h>

/* A demonstration of the variable number of arguments
 * feature in C.  Here, 'average' takes an arbitrary
 * (but known) number of arguments and averages them.
 *
 * The idea is from wikipedia:
 *    en.wikipedia.org/wiki/Varargs
 */
 
double average( int count, ... );

int main( void ) {
	printf( "The average of the digits is %lf\n",
	         average( 4, 3.52, 4.72, 4.19, 3.94 ) );

	printf( "The average of the digits is %lf\n",
	         (3.52 + 4.72 + 4.19 + 3.94)/4.0 );

	return 0;
}

double average( int count, ... ) {
	va_list ap;
	int i;
	double sum = 0.0;

	va_start( ap, count );

	for ( i = 0; i < count; i++ ) {
		sum += va_arg( ap, double );
	}

	va_end( ap );

	return sum/count;
}