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Python Python Basics Functions and Looping For Loops

Posted by nicolaspeterson
nicolaspeterson
8,569 Points

I did not understand anything in this video...

Can someone please please please explain what the difference is between while and for loops? I watched this video over and over and Craig loses me at the iterable-ness of strings. It's fun to run the same code he does and get the same result, but I don't understand what is going on.

1 Answer

Michael Cronk
Michael Cronk
8,969 Points

A very simple explanation is this:

A While loop will run until the loop is broken or interrupted. A For loop will run until the object/objects it's iterating over are at it's final value.

For an example: You can use a While loop when you are trying to ask a user input...

correct_num = 5

while True:
    user_guess = input("Guess a number between 1 and 5: ")
    user_guess = int(user_guess)
    if user_guess != correct_num:
        continue
    else:
        exit()

The code above will run UNTIL the user_guess is right.

A For loop will just iterate over an object, For example:

list_one = [1, 2, 3, 4, 5]

for val in list_one:
    print(val)

# prints out: 1, 2, 3, 4, 5

This will print all values in the list until it has finished running through it.

I hope this helped!

nicolaspeterson
nicolaspeterson
8,569 Points

Ok, this makes more sense now. Thank you!