Merge Sort (Array)

Cannot see what is wrong with my code: Currently trying to sort an array using merge sort.

Code:

#include <iostream>

#define SIZE 4

void mergeSort(float arraySorted[], float arrayTemp[], int LHS, int RHS);
void mergeBack(float arraySorted[], float arrayTemp[], int LHS, int middle, int RHS);

void main(){
	
	int Counter=0;
	float arrayOne[SIZE] = {65, -72, 54, 238};
	float arrayTwo[SIZE];



		for (Counter=SIZE-1;Counter>=0;Counter--){
			std::cout << arrayOne[Counter] << std::endl;
		}

	std::cout << "Something about sorting:" << std::endl;
	mergeSort(arrayOne, arrayTwo, 0, SIZE-1);

		for (Counter=SIZE-1;Counter>=0;Counter--){
			std::cout << arrayOne[Counter] << std::endl;
		}


	std::cout << "Blah" << std::endl;
}

void mergeSort(float arraySorted[], float arrayTemp[], int LHS, int RHS){

	int Counter, middle;

		if (RHS > LHS){
			middle = (LHS + RHS) / 2;

			mergeSort(arraySorted, arrayTemp, LHS, middle);
			mergeSort(arraySorted, arrayTemp, (middle+1), RHS);

			mergeBack(arraySorted, arrayTemp, LHS, middle, RHS);
		}

}

void mergeBack(float arraySorted[], float arrayTemp[], int LHS, int middle, int RHS){

	int LHSEnd, arraySize, arrayPosition, Counter = 0;

	LHSEnd = (middle -1);
	arrayPosition = (LHS);

		while ((LHS <= LHSEnd) && (middle <= RHS)){
			if (arraySorted[LHS] <= arraySorted[middle]){
				
				arrayTemp[arrayPosition] = arraySorted[LHS];
				arrayPosition = arrayPosition + 1;
				LHS = LHS + 1;

			}else{

				arrayTemp[arrayPosition] = arraySorted[LHS];
				arrayPosition = arrayPosition + 1;
				middle = middle + 1;

			}
		}

		while(LHS <= LHSEnd){
			
			arrayTemp[arrayPosition] = arraySorted[LHS];
			LHS = LHS + 1;
			arrayPosition = arrayPosition + 1;

		}

		while(middle <= RHS){

			arrayTemp[arrayPosition] = arraySorted[middle];
			middle = middle + 1;
			arrayPosition = arrayPosition + 1;
		
		}
		
		LHS=-SIZE-1;
		for(Counter=SIZE;Counter>=0;Counter--){
			arraySorted[LHS] = arrayTemp[LHS];
			LHS = LHS + 1;
		}

}

Also I am unsure of how to work out the Big-0 or how many procedures it requires to work this out.

If anyone can help me with either of my problems I would be very grateful.

Re Big-Oh: work your way through main (should be int main, btw). For each statement, add the Big-Oh orders. When adding them, remember that only the highest one matters.
For any nested loops, multiply the order.

For any function calls, calculate the Big-Oh for that function. Then you know that the function call will be of that order.
Eg, if merge_sort is O^2 and the rest of the code in main is O, then it is O + O^2 = O^2.
Repeat for ALL functions.

Thanks for the insight to Big-Oh: Do you have any idea what is wrong with my script, it just seems to outpute the same array in the same order after 'sort'. Cannot work out why...

You've got a copy and paste bug here:

Code:

				arrayTemp[arrayPosition] = arraySorted[LHS];
				arrayPosition = arrayPosition + 1;
				middle = middle + 1;

I would replace those three lines with just:

Code:

arrayTemp[arrayPosition++] = arraySorted[middle++];