Thread: Console window waiting on cin.ignore() or cin.ignore(2)

Why is it, that you have to use two lines like:

cin.ignore;
cin.ignore;

or one time:

cin.ignore(2);

to make the console window wait for a keypress.

One cin.ignore, doesn't seem to do the work

Code:

/**************************************************************
 * This program sums the numbers in a user-specified range,   *
 * omitting the if test that sets the upper and lower bounds. *
 **************************************************************/

#include <iostream>

using std::cin;
using std::cout;
using std::endl;

int main()
{
	int Num_1;
	int Num_2;
	int Num_one = 0;
	int Num_two = 0;
	int Range = 0;

	cout << "Exercise 1.20:" << endl << endl;
	cout << "Enter two numbers !" << endl << endl;
	cout << "Enter number one: ";
	cin >> Num_one;
	Num_1 = Num_one;
	cout << "Enter number two: ";
	cin >> Num_two;
	Num_2 = Num_two;

	if ( Num_1 < Num_2 )
		for ( Num_one = Num_one ; Num_one <= Num_two ; ++Num_one  )
		{
			Range += Num_one;

			if ( Num_one >= Num_two )
			{
				cout << endl << "The sum of all numbers from " << Num_1
				     << " to " << Num_2 << " is: " << Range << endl;
			}
		}

//	else if ( Num_one > Num_two )   // This works, but I "haven't learned" this
									// technique yet...
	if ( Num_1 >= Num_2 )
		for ( Num_two = Num_two ; Num_two <= Num_one ; ++Num_two  )
		{
			Range += Num_two;

			if ( Num_one <= Num_two )
			{
				cout << endl << "The sum of all numbers from " << Num_1
					 << " to " << Num_2 << " is: " << Range << endl;
			}
		}

	cout << endl << "Press [Enter] to exit... ;-)" << endl;
	cin.ignore(2);	// To make the console window, wait for a keypress !
	
	return 0;
}