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;
}

You typically don't use a cin.ignore to wait for a key press - you
use cin.get. The thing is, when you read in a value using
cin >> variable, say an int, when you press the enter key, the
enter key is left in the input buffer. The call to cin.ignore just
reads that value and discards it - if you use cin.ignore (2), and
there is only one character in the buffer, it'll wait for another
character (newline I mean) - thats's why you need cin.ignore (2).
Since there is typically only one newline in the buffer, the usual
format is:

Code:

//body of program

.
.
.

cin.ignore ();
cin.get ();

Hi Richie T


Oh, I see !

So I'll use:

Code:

cin.ignore();
cin.get();

To make my program discard the "Enter" keypress, and
then use cin.get() to wait for the new keypress "Enter/newline"

Flush the input buffer
Why does my program enter an infinite loop if the user inputs invalid data? (C++)
Stop my Windows Console from disappearing everytime I run my program?