The while loop

The while loop is used to run a section of the code repeatedly. This is useful if you have a set of actions that must be done repeatedly to accomplish some goal. For example, the while loop in the following code repeatedly prints the value of the variable x as it is incremented from 1 to 5:

int x = 1;
while( x <= 5 ) // may only enter the body of the while when x<=5
{
  cout << "x is " << x << endl;
  x++;
}
cout << "Finished" << endl;

This is the output of the preceding program:

x is 1
x is 2
x is 3
x is 4
x is 5
Finished

In the first line of code, an integer variable x is created and set to 1. Then, we go the while condition. The while condition says that while x is less than or equal to 5, you must stay in the block of code that follows.

Each iteration of the loop (an iteration means going once around the loop) gets a little more done from the task (of printing the numbers 1 to 5). We program the loop to automatically...