Sometimes algorithms have the need to repeat some actions
	Iteration is the same as repetition
	C++ many different iteration statements.

	while ( condition ) statement ;

	Wherever a statement is required you can use a single
	statement or a compound statement using
	{
		statement1; 
		statement2;
		statement3;
	}

	while statements require
		INITIALIZATION OF THE LOOP VARIABLES
		SET UP THE CONDITION 
		MAKE SURE THE CONDITION WILL EVENTUALLY BECOME FALSE

	Simple loop to compute the sum of numbers:
		int i, sum;
		i = 1;
		sum = 0;

		while (i <= 10)
		{
			sum = sum + i;
			i = i + 1;
		}

Common LOGIC error with loops are the following:

	1. Forgetting the initialization
	2. Not setting up the condition
	3. Forgetting the increment

READING INPUT FROM A FILE

	C++ provides the notion of a stream to make this convenient
	Once you create a stream, you can use the same insertion and
	extraction operators as you used with with cout and cin:
		<< is used for output from an output stream
		>> is used for input from an input stream

	#include <iostream.h>
	#include <fstream.h>

	// input file stream is associated with an external file
	ifstream inputfile("myinput.txt");
	if (inputfile == NULL)
	   cout << "File does not exist!" << endl;
	else
	  {
		int sum = 0, i;

		while ( (inputfile >> i) != NULL )
			sum = sum + i;
		cout << "Sum of numbers is: " << sum ;
	  }

WRITING OUTPUT TO A FILE

	ofstream outputfile("myoutput");
	outputfile << "Put this line in the output file" << endl;
	outputfile << i << j << k << endl;