How to Create Loops in Python

Learn how to create a loop using Python

Author Info

Last Updated: February 20, 2025

In Python, and many other programming languages, you will need to loop commands several times, or until a condition is fulfilled. It is easy, and the loop itself only needs a few lines of code.

Things You Should Know

If you are using IDLE, make sure all subprograms are off.
For a loop that goes for a definite amount of times, you will need a for loop, and for a loop that goes on forever you'll need a while loop.
You can use the break command to forcibly stop a loop. You can also use continue to skip to the next iteration of the loop.
Remember the if, elif and else words for your loops. They are useful keywords that you can use on your on your loop.

1

Open your shell or program.

Download Article

Make sure all subprograms are off if using IDLE.

2

Write a "for" loop.

Download Article

This is the structure for a for loop. The example prints "hello, world!" 10 times:

>>> for i in range(0, 10): # The first number specifies the start and the last one specifies the end
>>>      print("hello, world!")

This makes use of the range generator. It supports three arguments - start, stop and step, like so:

>>>  for i in range(0, 10, 2):
>>>      print(i)

This code will print 0, then 2, then 4, then 6, and keep going until 8. It increases by 2 each time (the step). The stop argument refers to the exclusive maximum value in the counter, so it will stop just before it.

3

Write a while loop.

Download Article

A method for both is shown. That will throw a SyntaxError unless you use Python version 2. It is recommended to use the above example of the print statement.

>>> while True: # This loop goes on forever
>>>       print "Hello World" # Prints the message which will not work on recent versions

4

Make the while loop last until a condition is met.

Download Article

In this example, True will always be True as long as the variable's answer and grade are Yes and 6. If they never changed, it will run forever so the while loop just makes the code loop while something is happening.

>>> while answer == "Yes" and grade == "6": # While the answer is equal to the string Yes and the grade to 6

5

Stop a loop.

Download Article

You can always kill the loop in Task Manager as well. The other way is using the break command or using while loops.
2
If you need to stop a loop inside the program, use break.

Community Q&A

Search

Add New Question

Question

How do you do a nested loop?

Adam Blalock

Community Answer

Here is a loop within a loop in Python: x = [0,1,2,3,4], y= [10,11,12,13]. For i in x: For ii in y: print i + ii. (Make sure to do it as a single tab before the second "For" and two tabs for the "print" statement.)

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 22 Helpful 4
Question

What about web development?

Community Answer

You need to learn about Django, the Python framework for web development.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 14 Helpful 3
Question

How do you use a while loop to repeat a calculator program?

Community Answer

First create a function. For example, if you wanted to square numbers 1 through 100 and print the results to the screen, I would write: def square(x): return x*x for i in range(1, 101): # stop = 101 because the stop value is not included. This will go from 1-100. print(square(i)).

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 12 Helpful 5

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Video

Tips

You can exit a loop prematurely with the break command. This might be needed, for example, if you're iterating over a list to find something and can stop looking once you've found it.

Thanks
Helpful 0 Not Helpful 0
You can use the continue command to skip to the top of the loop. This is useful if you wanted to skip certain code if a condition is met.

Thanks
Helpful 0 Not Helpful 0
Avoid using the while True loop without any "break" commands or keywords that end it.

Thanks
Helpful 0 Not Helpful 0