stdlib-qsort.c

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

#include <string.h>


#ifndef NELEM
#define NELEM(pole) (sizeof pole/sizeof *pole)
#endif

char *jmena[] = {"Myspulin","Fifinka","Pinda","Bobik"};

int    inty[] = { 2, 6, 1, 4};

double dbly[] = { 2.0, 6.1, 1.2, 4.5};

/* TODO: udelat compare funkce verejne! vyuzije je i bst_tree, bsearch ... */

static int str_asc (const void *a, const void *b) { return strcmp(*(char **)a, *(char **)b); }

static int int_asc (const void *a, const void *b) { return *(int *)a - *(int *)b; }
static int int_desc(const void *a, const void *b) { return *(int *)b - *(int *)a; }//sestupně

static int dbl_asc(const void *a, const void *b) {
  return *(double *)a > *(double *)b ? 1 : -1;// equal: vracet 0 neresime?
}

/* deklarace ze stdlib.h:
void qsort(void *base, size_t nmemb, size_t size, int(*compar)(const void *, const void *));
*/

int main(void) {
  int i;
  for(i=0; i<NELEM(jmena); i++){ printf("%c\"%s\"", i?',':'{', jmena[i]);} ; printf("}\n");
  qsort(jmena, NELEM(jmena), sizeof *jmena, str_asc);
  for(i=0; i<NELEM(jmena); i++){ printf("%c\"%s\"", i?',':'{', jmena[i]);} ; printf("}\n");

  qsort(inty, NELEM(inty), sizeof *inty, int_desc);
  for(i=0; i<NELEM(inty); i++){ printf("%c%6d", i?',':'{', inty[i]);} ; printf("}\n");

  qsort(dbly, NELEM(dbly), sizeof *dbly, dbl_asc);
  for(i=0; i<NELEM(dbly); i++){ printf("%c%6g", i?',':'{', dbly[i]);} ; printf("}\n");

  return 0;
}