#include <stdlib.h>  #include <stdio.h>    static void swap(void *x, void *y, size_t l) {     char *a = x, *b = y, c;     while(l--) {        c = *a;        *a++ = *b;        *b++ = c;     }  }    static void sort(char *array, size_t size, int (*cmp)(void*,void*), int begin, int end) {     if (end > begin) {        void *pivot = array + begin;        int l = begin + size;        int r = end;        while(l < r) {           if (cmp(array+l,pivot) <= 0) {              l += size;           } else {              r -= size;              swap(array+l, array+r, size);           }        }        l -= size;        swap(array+begin, array+l, size);        sort(array, size, cmp, begin, l);        sort(array, size, cmp, r, end);     }  }    void qsort(void *array, size_t nitems, size_t size, int (*cmp)(void*,void*)) {     sort(array, size, cmp, 0, (nitems-1)*size);  }    typedef int type;    int type_cmp(void *a, void *b){ return (*(type*)a)-(*(type*)b); }    main(){ /* simple test case for type=int */    int num_list[]={5,4,3,2,1};    int len=sizeof(num_list)/sizeof(type);    char *sep="";    int i;    qsort(num_list,len,sizeof(type),type_cmp);    printf("sorted_num_list={");    for(i=0; i<len; i++){      printf("%s%d",sep,num_list[i]);      sep=", ";    }    printf("};\n");  }