Thread: Throw away members in qsort

Code:

/* I need help 
How can I move away from qsort all members that are not have enought points */
/* I wanna do some filer function (base on qsort) that throw away all field elements that doesent satisfy criterion (what is incoming argument of function filer)*/
/* In function does_have_enought_points all members with let's say udenr 100 points. drop out*/

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

#define MAX 1024
#define MAXS 128

struct student{
       char name[MAX];
       char lastname[MAX];
       int points;
};

typedef struct student STUDENT;

int does_have_enought_points( const void *a )
{
}

void filter( void *base, int *num, int width, int(*fn_criterion)(const void*))
{
}


int compare_points(const void *a, const void *b)
{
    return ( ((STUDENT*)a)->points - ((STUDENT*)b)->points);
}


void load( STUDENT a[MAXS], int n)
{
     int i;
     for(i = 0; i < n; i++)
     {
           printf("Insert name: "); scanf("%s", &a[i].name);
           printf("Insert lastname: "); scanf("%s", &a[i].lastname);
           printf("Insert points: "); scanf("%d", &a[i].points);
     }
}

void write_out( STUDENT a[MAXS], int n)
{
     int i;
     for( i = 0; i < n; i++ )
     {
          printf("%s ", a[i].name);
          printf("%s ", a[i].lastname);
          printf("%d ", a[i].points);
          printf("\n");
     }
}

int main()
{
    STUDENT a[MAXS];
    int n = 0;

    printf("How many students do you wanna enter?\n");
    scanf("%d", &n );
    load( a, n );

    filter( a, &n, sizeof(STUDENT), does_have_enought_points);
    write_out( a, n );

    qsort( a, n, sizeof(STUDENT), compare_points);
    write_out( a, n );

    return 0;
}