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Python 2 had another way of formatting
strings, called string interpolation.

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Just a reminder here, that if you want to download the slides, you can do so. All the

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details are right here in this bonus video.

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Right down at the bottom of this course. The very last video in fact, in the course. So just watched that video,

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it's got all the details

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you need, to be able to download those slides. if you want to do that and be able to access them offline

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What I'm going to do is create a new file.

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We're going to call that
interpolation.

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Now the Python 2 formatting operator is the % and
it's followed in the string by a letter,

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to indicate how the formatting should
work. So I'm going to start by typing age = 24 on line 1.

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Line 2, I'm going to type print parentheses double quote,
or quotes rather,

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My age is, and the percent sign, as I mentioned, d years,

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and a closing double quote space, and % age, and closing right parenthesis. So here the %d will

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be replaced by an integer value that's
provided after the string, following

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another % character. So if we run
that, just to confirm that it works,

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and there's the output: My age is 24 years. Now if
you wanted to inject a float into a

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string we'd use %f, and then we'll
have to provide a string, and to provide

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a string we'd use %s. Let's have
a look at both of those, with some code.

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I'm going to start on line 4 by typing major
= "years". Line 5 minor = "months"

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and then I continue typing on line 6, print
double quotes My age is %d

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space %s comma %d space %s

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and then our double quote, and then outside of that

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I'm gonna put in parentheses, age, major, 6, minor,

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and the two closing right parentheses. And we'll
continue on with an example using PI

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again on line 7, print parentheses double
quotes Pi is approximately %f

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double quote and the % again, parentheses 22 divided by 7 and two right parentheses.

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And I forgot to put the percent sign, of
course, and we need to do that on line 6.

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Okay. So starting on line 6, the first
%d is replaced by the first

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variable, age, then the first %s is
replaced by the string variable, major.

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The second %d is replaced by the
value 6 and the final %s

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is replaced by the string variable, minor.
Replacement is strictly one value at a

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time, from left to right, with none of the
flexibility offered by Python 3's

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replacement fields. So moving on to line
7, we've used %f to represent the floating-point result.

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So if we run this now, and you see we get the relevant results.

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Alright, so now that we've run
that, you can also specify the precision

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of the number. What I'm going to do is
duplicate line 7, then we'll add

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add the precision as well. And the way we
do that, instead of just putting %f there,

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we change the percent. We type
60.50 to specify the precision and then we run that.

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You can see we get the, basically, a similar

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result to when we were using a
replacement field. So as well as %d, %s

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and %f, we can also use %x to display
numbers in hexadecimal, %o for

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octal and %e for scientific
notation - along the lines of one

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1.23456e+09, for example. Now there are more modifiers

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and conversion types, and these are
presented in tables in the Python Docs.

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So I'll just quickly load that up and
show you that link.

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So check this out for more information on this page.
Once again, though, I've mentioned these

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so that you'll understand them when reading
code from the internet, and if you end up

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using Python 2. You shouldn't be using
these in Python 3 code. Alright, so let's

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move onto the next video, which is a
quick summary of what we've been through in this section.

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See you in the next
video.