passing arguments to a function

[cfanatic]

Hi folks!

The code below is from an old C textbook that I'm working through.

I can see the function intcmp called within qsort and bsearch, but I can't see any arguments passed to it. So how is the intcmp function getting values for v1 and v2?

Thanks in advance!

/* Using qsort() and bsearch() with values.*/

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

#define MAX 10

int intcmp(const void *v1, const void *v2);

int main( void )
{
     int arr[MAX], count, key, *ptr;

     /* Enter some integers from the user. */

     printf("Enter %d integer values; press Enter after each.\n", MAX);

     for (count = 0; count < MAX; count++)
         scanf("%d", &arr[count]);

     puts("Press Enter to sort the values.");
     getc(stdin);

     /* Sort the array into ascending order. */

     qsort(arr, MAX, sizeof(arr[0]), intcmp);

     /* Display the sorted array. */

     for (count = 0; count < MAX; count++)
         printf("\narr[%d] = %d.", count, arr[count]);

     puts("\nPress Enter to continue.");
     getc(stdin);

     /* Enter a search key. */

     printf("Enter a value to search for: ");
     scanf("%d", &key);

     /* Perform the search. */

     ptr = (int *)bsearch(&key, arr, MAX, sizeof(arr[0]),intcmp);

     if ( ptr != NULL )
         printf("%d found at arr[%d].", key, (ptr - arr));
     else
         printf("%d not found.", key);
     return 0;
}

int intcmp(const void *v1, const void *v2)
{
     return (*(int *)v1 - *(int *)v2);
}

[laserlight]

I can see the function intcmp called within qsort and bsearch, but I can't see any arguments passed to it.

Yes, because a pointer to intcmp is passed to qsort.

So how is the intcmp function getting values for v1 and v2?

qsort passes those arguments when it calls intcmp using the function pointer you passed to it.

[cfanatic]

Thanks laserligt!