Room for Prateek Mourya and John Rennie

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Prateek Mourya

08:16

hello @JohnRennie sir

John Rennie

Hi :-)

Prateek Mourya

can you explain for loops

John Rennie

Can you say what about them you are having difficulty with? So I know where to start.

Prateek Mourya

the begning of it is not explained in proper way

he starts out by saying

to print items of a list

use for item in list:

print(item)

but how does this code work

John Rennie

In Python many objects are iterable. This sounds complicated but it just means the objects are made up from several components and you can step through the components one by one. OK so far?

Prateek Mourya

08:22

John Rennie

For example a list is iterable because it contains elements l[0], l[1], etc and you can step though the elements in the list using an integer 𝑖 where 𝑖 goes from 0 up to the length of the list.

Prateek Mourya

John Rennie

And in Python for loop is a way of iterating through any iterable object. For example the code:

for i in mylist:
    print(i)

will step through every element in mylist setting the variable i to each element of the list in turn.

So this will print each element of the list.

Does this make sense so far?

Prateek Mourya

if it is a loop

how does it know everytime

to set i to next element

in every other cycle

John Rennie

The for loop keeps track of which element it is looking at, so once it has done that element it knows what the next element is. All this is done for you by the Python interpreter so you don't need to know exactly how it is done.

If you are curious I can point you to web pages explaining exactly how it works, but i wouldn't worry about for now.

Prateek Mourya

08:30

@JohnRennie ok

John Rennie

That's pretty much all you need to know about for loops. They will step through any iterable object.

Prateek Mourya