The for loop is typically used to iterate through a fixed set of values that can be determined before the loop executes. This is why we say that a for loop exhibits definite iteration.
On the other hand, the while loop is more flexible, as we saw with the example of validating user input. In that case, we could not determine in advance how many times the loop would iterate; it depended entirely on the values provided by the user during program execution. For this reason, a while loop is often described as indefinite iteration. We expect that eventually the condition controlling the iteration will evaluate to false and the iteration will stop. (Unless we have an infinite loop, which is a problem we want to avoid.)
While we saw that any for loop can be written as a while loop by manually creating and updating a loop variable, it is preferable to use a for loop when iterating over a collection or iterating a fixed number of times. Manually updating the variable in a while loop is more work for you, the programmer, and can lead to infinite loops if not handled properly.
Question
You are asked to program a robot to move tennis balls from one box (Box #1) to another (Box #2), one-by-one. The robot should continue moving balls until Box #1 is empty, and balls may be added to the box after the robot begins its work.
Which type of loop should you use to write the program?
while loopfor loopQuestion
You are asked to write a program similar to the one above, with the modification that a user may give the robot a specific number of balls to move from Box #1 to Box #2. (You can assume there will always be more balls than the user has asked the robot to move.)
Which type of loop should you use to write the program?
while loopfor loop