C implementation of quicksort which colors the values being swapped for instructional purpouses.

quicksortcolor.c

/*
Algorithm Practice: Quicksort
*/

#include <stdio.h>

#define ARRAY_LENGTH 32

int array[ARRAY_LENGTH]; // The array to be sorted

int setup(int array[]){
	// Fill the array with random numbers.
	int i;
	for (i=0; i < ARRAY_LENGTH; i++) {
		array[i] = rand() % ARRAY_LENGTH;
	}
}

void report(int array[], int len){
	// Report the contents of an array
	int i;
	for (i = 0; i < len; i++){
		printf("%02d ", array[i]);
	}
	printf("\n");
}

void creport(int array[], int len, int ilow, int ihigh){
	// Report the contents of an array
	int i;
	for (i = 0; i < len; i++){
	    if (i == ilow){
	        printf("\033[32m%02d\033[0m ", array[i]);
	    } else {
	        if (i == ihigh){
	            printf("\033[33m%02d\033[0m ", array[i]);
	        } else {
	            printf("%02d ", array[i]);
	        }
	    }
	}
	printf(" (%02d and %02d) \n", array[ilow], array[ihigh]);
}

void quicksort(int lbound, int rbound, int array[]){
	int i, j, pivot;
	i = lbound;
	j = rbound;
	int tmp;
	pivot = array[(lbound + rbound) / 2];

	while (i <= j){
		while (array[i] < pivot){
			i++;
		} // At this point, we have found a misplaced number; Now to find something to swap it with.
		while (array[j] > pivot){
			j--;
		}
		// Now, we swap the two numbers:
		if (i <= j){
			tmp = array[j];
			array[j] = array[i];
			array[i] = tmp;
			creport(array, ARRAY_LENGTH, i, j);
			i++;
			j--;
		}
	};
	if (lbound < j){
		quicksort(lbound, j, array);
	}
	if (i < rbound){
		quicksort(i, rbound, array);
	}
}

int  main(){
	// Setup and sort the array.
	printf("Setting up array...\n");
	setup(array);
	report(array, ARRAY_LENGTH);
	printf("Done, sorting array...\n");
	quicksort(0, ARRAY_LENGTH-1, array);
	printf("Done sorting.\n");
	report(array, ARRAY_LENGTH);
	return 0;
}