/************************************************************************
 *
 * Purpose: To read numbers entered by the user and sort them.
 * Author:  M.J.Leslie
 * Date:    30-Nov-94
 *
 ************************************************************************/

/********** Preprocessor  ***********************************************/

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

/********** Functions ***************************************************/

int read_nums(int *);
void display_nums(int *);
int comp_nums(const int *, const int *);

/********** main ********************************************************/

main()
{
    int numbers[30];			/* Numbers to be sorted.	*/
    int how_many=0;			/* Number of numbers entered	*/

					/* Get the numbers		*/
    how_many = read_nums(numbers);

    puts("\nThese are the unsorted numbers\n");
    display_nums(numbers);

					/* SORT the numbers held in 
					 * 'numbers'.			*/
    qsort(
	  numbers, 			/* Pointer to elements		*/
	  how_many, 			/* Number of elements		*/
	  sizeof(int),  		/* size of one element.		*/
	  (void *)comp_nums		/* Pointer to comparison function */
	  );

    puts("\nThese are the sorted numbers\n");
    display_nums(numbers);
}

/************************************************************************
 *
 * comp_nums: Compare two numbers.
 *
 ************************************************************************/

int comp_nums(const int *num1, const int *num2)
{
    if (*num1 <  *num2) return -1;
    if (*num1 == *num2) return  0;
    if (*num1 >  *num2) return  1;
}

/************************************************************************
 *
 * readnums: read numbers from the keyboard and put them into an array.
 *
 ************************************************************************/

int read_nums(int *array)
{

    char data[80];			/* Data entered by the user	*/
    int inc=0;

    puts("\n\tPlease enter some integer numbers");
    puts("\tno checking is made on the data you enter....");
    printf("\t==> ");

    gets(data);
					/* Assume we have valid data.	
					 * Put it into an array.	*/
    *(array+inc) = atoi(strtok(data," "));
    inc++;
   
    while ( *(array+inc) = atoi(strtok(NULL," "))) inc++;

					/* Return the number of items
					 * stored in 'array'.		*/
    return inc++;
}

/************************************************************************
 *
 * display_nums: Display the numbers
 *
 ************************************************************************/

void display_nums(int *array)
{
					/* NULL is a pointer to 0, 
					 * so it must be cast to an
					 * integer			*/
    while ( *array != (int)NULL)
    {
        printf("%d ",*array);
        array++;
    }

    puts("");
}