C Library Functions - qsort ()

C standard library - <stdlib.h>

description

C library functionsvoid qsort (void * base, size_t nitems, size_t size, int (* compar) (const void *, const void *)) to sort the array.

statement

Here is the qsort () function's declaration.

void qsort(void *base, size_t nitems, size_t size, int (*compar)(const void *, const void*))

parameter

• base - a pointer to the first element of the array to be sorted.
• nitems - the number of points to the base of the array elements.
• size - the size of each element in the array, in bytes.
• compar - function used to compare two elements.

return value

This function does not return a value.

Examples

The following example demonstrates the qsort () function is used.

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

int values[] = { 88, 56, 100, 2, 25 };

int cmpfunc (const void * a, const void * b)
{
   return ( *(int*)a - *(int*)b );
}

int main()
{
   int n;

   printf("排序之前的列表：\n");
   for( n = 0 ; n < 5; n++ ) {
      printf("%d ", values[n]);
   }

   qsort(values, 5, sizeof(int), cmpfunc);

   printf("\n排序之后的列表：\n");
   for( n = 0 ; n < 5; n++ ) {
      printf("%d ", values[n]);
   }
  
  return(0);
}

Let's compile and run the above program, which will result in the following:

排序之前的列表：
88 56 100 2 25 
排序之后的列表：
2 25 56 88 100

C standard library - <stdlib.h>