Some Great Examples of recursion C++

This little program demonstrates the recursion technique in three different settings.  It includes recursive algorithms to search an array, reverse a number, and find the greatest common divisor of two numbers.

// Boyd Turley 
#include <iostream>
#include <string>
#include <fstream>
#include <iomanip> //required to use setw()
#include <cstdio>

using namespace System;
using namespace std;
///////////////////////////////////// Globals
const int TABLE_ROWS = 30;
const int TABLE_COLS = 20;
int table[TABLE_COLS][TABLE_ROWS];
int grid[599];

//////////////////////////////////// FXN Defs.
bool posWhole(int checkme);

void NumReverse(int reverseme);

void setOrder(int num1, int num2);

int GCD(int num1, int num2);

void gridSearch();

///////////////////////////////////////////////////////////////////////////////////////// MAIN
int main(array<System::String ^> ^args)
{
	char thechoice = 0;
		
		while(thechoice != '!')
		{
			system("cls");
			cout << "Recursion Menu:"<<endl
			 << "S.  Search an array for a number." << endl
			 << "M. Mirror a number." << endl
			 << "G. Greatest Common Devisor." << endl
			 << "Q. Quit Program." << endl;
			cin >> thechoice;

		switch(thechoice)
		{
			int num;
			case 'S':
			case 's':
				{
					system("cls");
					gridSearch();
					cout << endl;
					system("pause");
					break;
				}
			case 'M':
			case 'm':
				{
				system("cls");
				cout << "Enter the number to be mirrored" << endl << "nt";
// validate positive and whole
				if(!(cin >> num))
				{
					cout << "thats not a int, try again.";
					thechoice = '#';
										
								// {// flush cin buffer somehow...}
					
					system("pause");
					break;
				}
				NumReverse(num);
				break;
				}
			case 'G':
			case 'g':
				{
					system("cls");
					unsigned int num1,num2;
					cout << "Enter two intigers to find their GCD"<<endl;
					cin >> num1 >>num2;
					cout << GCD(num1,num2) << endl;
					system("pause");
					break;
				}
			case 'Q':
			case 'q':
				{
					thechoice  = '!';
					break;
				}
			default:
				{
					cout << "Enter S, M, G, or Q followed by the enter key.nn";
					cin.clear();

					system("pause");
					break;
				}
		}}


		cout << "ntend Of progn";
		system("pause");
	return 0;
}

///////////////////////////////////////////////////////////////////////////////////////// FXN METHODS
bool posWhole(int checkme)
{
	return true;
}

void NumReverse(int reverseme)
{
	if(reverseme<=0)
	{	cout << "Bad Input";
		system("pause");
		return;
	}
	else{
		//base case: 1 digit.
		if((reverseme/10) < 1)
		{
			cout << reverseme << "...is the mirrored number." << endl;
			system("pause");
			system("cls");
			return ;
		}
		//recursive step:
		cout << (reverseme%10);
		NumReverse(reverseme/10);
	}
}

void setOrder(int num1, int num2)
{
	if(num1>num2)
	{
		int tempswap = num1;
		num1 = num2;
		num2 = tempswap;
	}
}

int GCD(int num1, int num2)
{
	setOrder(num1,num2);
	while(num1<=0 || num2<=0)
	{
		cout << "No negative numbers"<<endl;
		cin >> num1 >> num2;
	}
	if(num1%num2 ==0)
	{
		return num2;
	}
	return (GCD(num2,(num1%num2)));
}

void gridSearch()
{
	int findme=0;
		ifstream in;
	in.open("values.txt");
	if(!in)	//crap on invalid input
	{
		cout << "Wrong file, Ya Hippyn";
		system("pause");
		return;
	}

	int i,tmp,gridctr = 0;
	cout<<"n   ";
			for(i=0;i<TABLE_COLS;i++)//print top row

			{
				cout <<setw(4)<< i;
			}
			cout << endl;
	while(!in.eof()) // File reading begins here
	{
		for(i=0;i<TABLE_ROWS;i++)// FOR EACH ROW
		{
			for(int j=0;j<TABLE_COLS;j++) //FILL ITS COL VALUES
			{
				//char tmp;
				if(j==0) //insert a left margin
					cout<<endl<<setw(3)<<i;
				in >> tmp;
				cout << setw(4)<< tmp; 
				
				//grid[TABLE_ROWS][TABLE_COLS] = tmp;    //write tmp to array   
				
				//the above doest nothing at all????!!! Driving me friggin crazy!!!!
				//I cant even attempt to search the grid without properly loading it.
				// im punking out and using a regular array
				grid[gridctr] = tmp;
				gridctr++;
			}
		}
	}
	// failed recursion attempt

	//int low = 0;
	//int high = 599;
	//cout << "nEnter a number to Locate";
	//cin >> findme;
	//if(findme == grid[(high-low)/2])
	//{                                    
	//	cout << "nnumber found at row:" << (i%20) << "  col:" << (grid[(high-low)/2]%20);
	//}
	//else{
	//	if(findme < grid[(high-low)/2])
	//	{
	//		return;                            //cant figure out how to modularize and still be able to lookup the grid
	//	}
	//}
	
	//iterative punkout... gotta turn in something that runs..
	
	while(findme>=0)
	{
		cout << "nEnter a number to Locate. Any negative entry will exit";
		cin >> findme;
		i=0;
		while(grid[i] <= findme)
		{
			if(grid[i]==findme)
				cout << "nnumber found at row:" << (i/20) << "  col:" << (i%20);
			i++;
		}
	}findme=0;	
}