Array shuffle and unshuffle

arrayshuffle.c

#include <stdio.h>

int * shuffle(int * array, int seed, int index, int len);
int * unshuffle(int * array, int seed, int index, int len);
void swap(int * num1, int * num2);
void printArray(int * array, int len);

int main()
{
	int vec[5] = {1, 2, 3, 4, 5};
	shuffle(vec, 1, 0, 5);
	printArray(vec, 5);
	puts("\n");
	unshuffle(vec, 1, 0, 5);
	printArray(vec, 5);
	return 0;
}

int * shuffle(int * array, int seed, int index, int len)
{
	int result;
	if(index == len)
		return array;
	srand(seed);
	result = rand();
	swap(&array[index], &array[result%len]);
	return shuffle(array, result, index + 1, len);
}

int * unshuffle(int * array, int seed, int index, int len)
{
	int result;
	if(index == len)
		return array;
	srand(seed);
	result = rand();
	array = unshuffle(array, result, index + 1, len);
	swap(&array[index], &array[result%len]);
	return array;
}

void swap(int * num1, int * num2)
{
	int temp = *num1;
	*num1 = *num2;
	*num2 = temp;
}

void printArray(int * array, int len)
{
	int i;
	for(i = 0; i < len; i++)
		printf("array[%d] = %d\n", i, array[i]);
}