Programming Loops

What is the primary capability provided by loops in computing?

What type of loop is preferred when the number of iterations is unknown?

What is the term for each repetition of a loop body?

What happens when a new assignment is made to an existing variable?

What is the purpose of a sentinel value in a loop?

What type of loop is used when the number of iterations is known?

What is the general term for structures that allow for repetition in programming?

What happens to the old object when a new assignment is made to an existing variable?

What is the purpose of a loop variable in a while loop?

What is the order of execution in a while loop?

What is a characteristic of a while loop?

What happens if the expression in a while loop is false before the loop?

What is the purpose of the 'break' statement in a loop?

How do for-each loops handle Loop Control Variables (LCVs) in Python?

What is an infinite loop?

What is a common problem with using loop variables like 'i' or 'j'?

Loops are the second major part of control flow, after branching.
A loop lets you repeat a block of code (the loop body), and each repetition is known as an iteration.

There are two kinds of loops:
- Sentinel loops, which have a sentinel value that triggers the termination of the looping, and are preferred when you don’t know how many iterations the problem will take.
- Counting loops, which are used when you know a-priori how many times you wish the loop body to repeat.

A loop control variable (LCV) is a variable that is used to control the loop.
In Python, while loops handle LCVs explicitly, and for-each loops handle LCVs implicitly.
In other languages, C-style for loops manage LCVs explicitly.

An infinite loop is a loop that has no termination condition, causing it to repeat indefinitely.

In most languages, you can exit a loop early using:
- Break: exits the loop completely.
- Continue: skips the current iteration and continues with the next iteration.
- Return: exits the loop and returns a value from a function.

To debug loops, you can use various techniques such as:
- Printing out variables and expressions to see their values.
- Using a debugger to step through the code.

The syntax for a while loop is: while expression: statement(s).
A while loop is a pre-test loop, which means that the condition is checked before the body of the while loop is executed.
If the condition is false, the body of the loop is not executed.