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In programming languages such as C or
Java, for loops work differently.

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In those languages, you provide a starting value
and an ending value, and increment a

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variable each time around the loop.
Python's different approach to for loops

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makes them incredibly powerful but also
very flexible. We can get the same effect

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as C for loops, by iterating over a range
of values. So let's take a look at that.

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What I'm going to do is create a new file
here. We're gonna call this one ranges.py.

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Now be careful here with what I've just
done. You can get problems if you'd

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called the file range without an s,
because its name will conflict with

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pythons range class. That's why I called
this one ranges.py. Alright so let's

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have a go at printing out the values
from 1 to 20. We'll use a range object

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and give it the starting and ending
values; for i in range parentheses

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1 comma 20, and the closing parentheses
colon. Next line, print parentheses double

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quotes i is now. Then within the double
quotes, left and right curly braces

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closing double quote dot format
parentheses i in the parentheses and the

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two closing right parentheses. We'll talk
more about naming variables in a later

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video. Up till now, we've just been using
simple words that describe the values

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we've been dealing with. Normally, you
should avoid using single character

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names for variables, as they don't give
any indication of what the variable is

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for. Loop control variables, however, are
one of the few places where names like

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i or j are acceptable. i is taken to be short
for index, and the convention is that it

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is an acceptable name in a for loop, as
we're using here. Now when we run the

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program, which I'll do now, you can see the
output on the screen and you can see

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that it almost works. The range was
actually outputted from 1 to 19.

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So in other words, 20 isn't included here
and you can see clearly that we use the

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numbers 1 to 20 on line 1. So do you
remember how our strings slices

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returned the characters up to, but not
including, the end number? Well ranges

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work in the same way. The last value specified

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is not included. range produces a range
of numbers from the starting value, up to

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but not including the end number, or the
end value. To include the value 20 in our

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loop, therefore, we need to change the stop
value to 21. So I'm gonna go ahead and do that,

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and this time when I run the program we
should see the values from 1 to 20.

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You can see there that we've now got the
correct output. So experiment with

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different values in the range to
understand what it's doing. For example,

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you could try the following:
I'll change 1 to 21 to 10

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to 16, and that would give us the
numbers in the range of 10 through 15,

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and you can see that is the case with the
output at the bottom of the screen.

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When you're happy with that, I'll
see you in the next video.