/* simple qsort demo */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int idcomp( const void *p1, const void *p2 ); /* compare id */
int frcomp( const void *p1, const void *p2 ); /* compare fruits */

struct idtable {
	int id;
	char *fruits;
};

main()
{
	int i, n;

	struct idtable a[] = {
		{ 32, "banana"},
		{ 23, "orange"},
		{ 17, "pine apple"},
		{ 42, "apple"},
		{ 13, "lemon"},
		{ 51, "papaya"},
		};

	n = sizeof( a ) / sizeof( a[0] );

	printf( "Before sorting...\n" );
	for( i = 0; i < n; i++ ) 
		printf( "%5d  %5d %s\n", i, a[i].id, a[i].fruits );

	qsort( a,                  	/* address of array to be sorted */
	       n,                	/* number of elements in array */
	       sizeof( a[0] ), 	  	/* size of an element */
	       idcomp );             	/* function to compare */

	printf( "After sorting by id...\n" );
	for( i = 0; i < n; i++ )
	 	printf( "%5d  %5d %s\n", i, a[i].id, a[i].fruits );

	qsort( a,                  	/* address of array to be sorted */
	       n,                	/* number of elements in array */
	       sizeof( a[0] ), 	  	/* size of an element */
	       frcomp );             	/* function to compare */

	printf( "After sorting by fruits...\n" );
	for( i = 0; i < n; i++ )
	 	printf( "%5d  %5d %s\n", i, a[i].id, a[i].fruits );

	return( 0 );
}

int idcomp( const void *p1, const void *p2 )
{
	struct idtable *t1, *t2;

	t1 = (struct idtable *)p1;
	t2 = (struct idtable *)p2;
	return t1->id - t2->id;
}

int frcomp( const void *p1, const void *p2 )
{
	struct idtable *t1, *t2;

	t1 = (struct idtable *)p1;
	t2 = (struct idtable *)p2;
	return strcmp(t1->fruits, t2->fruits );
}