Generic Bubble Sort Library in C

Sort arrays of any type with a custom comparator function in C using the bubble sort algorithm.

No preprocessing using macros and no use of _Generic, just pure C.

Usage

Sorting an array is done using the sort function:

void sort(void *arr, size_t n, size_t value_size, int (*cmp)(void*,void*));

• void *arr: pointer to the array to be sorted
• size_t n: size of arr
• size_t value_size: size of the elemens of arr
• int (*cmp)(void*,void*): callback function used for comparison

A comparator function used in place of cmp has to apply the following rules:

• Accept two pointers to be compared with. These two values have to be cast to the appropriate type, e.g. to int* in cmp_int.
• Return an int indicating the ordering with the below scheme:
  • If left > right return a value greater than zero
  • If left < right return a value less than zero
  • If left == right return zero

Implementation of cmp_int

int cmp_int(void *v1, void *v2) {
    int *p = v1, *q = v2; // implicit cast to int*
    if (*p > *q) return 1;
    else if (*p < *q) return -1;
    else return 0;
}

Comparators are user-defined and can for example be used to do descending sorting, whatever the user intends to do.

The goal is for users of this library to sort any type by just having to implement a comparator which then can be provided to the sort function.

Exmaple usage

Sorting an array of integers using the library provided cmp_int comparator:

#include "generic_bubble_sort.h"

/* Sort an array of integers using cmp_int */

int arr[] = { 3, 2, 5, 1 }; 
size_t arr_len = sizeof(arr) / sizeof(arr[0]);

sort(arr, arr_len, sizeof(arr[0]), cmp_int);

/* Array after sort: { 1, 2, 3, 5} */