This program demonstrates an algorithm for deleting duplicate values of type char in an array.

(C++) Delete Duplicates

//This program demonstrates an algorithm for deleting duplicate values of type char in an array.

#include "stdafx.h"
#include <iostream>
using std::cout;
using std::endl;

void DeleteRepeats(char a[], int& numberUsed);
//Precondition: numberUsed is <= declared size of a. a[0] through a[numberUsed - 1] have values of type char.
//Postcondition: All duplicate values in a have been deleted, and numberUsed has been adjusted to reflect
//its appropriate value after any elements were deleted.

void Output(const char a[], const int numberUsed);
//Precondition: numberUsed <= declared size of a. a[0] through a[numberUsed - 1] have values of type char.
//Postcondition: Outputs a[0] through a[numberUsed - 1] with spaces between each.

void RemoveFromArray(char a[], int startingIndex, int& numberUsed);
//Precondition: numberUsed <= declared size of a. a[0] through a[numberUsed - 1] have values of type char.
//a[startingIndex] is the element to be removed from a.
//Postcondition: a[startingIndex] has been removed from the array.
//a[startingIndex + 1] through a[numberUsed] shifted one index left. numberUsed decremented by one.

void LineSpace();
//Ouputs endl twice.

int main()
{
	int arraySize1 = 5;
	int arraySize2 = 5;

	char myArr1[] = { 'a', 'a', 'b', 'c', 'a' };
	char myArr2[] = { 'x', 'y', 'y', 'z', 'x' };

	DeleteRepeats(myArr1, arraySize1);
	DeleteRepeats(myArr2, arraySize2);

	Output(myArr1, arraySize1);

	LineSpace();

	Output(myArr2, arraySize2);

	LineSpace();

	return 0;
}

void DeleteRepeats(char a[], int& numberUsed)
{
	for (int i = 0; i < numberUsed - 1; i++)
	{
		for (int j = i + 1; j < numberUsed; j++)
		{
			if (a[i] == a[j])
			{
				RemoveFromArray(a, j, numberUsed);
				j--;
			}
		}
	}
}

void Output(const char a[], const int numberUsed)
{
	for (int i = 0; i < numberUsed; i++)
	{
		cout << a[i] << " ";
	}
}

void LineSpace()
{
	cout << endl << endl;
}

void RemoveFromArray(char a[], int startingIndex, int& numberUsed)
{
	numberUsed--;
	for (startingIndex; startingIndex < numberUsed; startingIndex++)
	{
		a[startingIndex] = a[startingIndex + 1];
	}
}