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>> SPEAKER 1: The last time we analyzed
integers, recall that we used some

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Boolean expressions to check if a user's
input n was between numbers

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like 0 and 3, 4 and 7, and 8 and 10.

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Well, we did that using if's and else
if's, but it turns out you can

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implement that same logic using a
different programming construct

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altogether while still achieving
precisely the same result.

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In fact, we can introduce something
called a switch that allows us to

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switch our behavior depending on
the value of some variable.

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>> Let's give this a try.

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To do this, I'm first going to include
the cs50 library by way of cs50.h.

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I'm also going to include the standard
library by way of standard I/O.h.

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And I'm going to declare main in
the usual way, int main void.

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Open curly brace.

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Close curly brace.

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And now I'm going to ask the
user for an integer.

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>> Printf, give me an int
between 1 and 10.

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And now I'm going to get
that int using the cs50

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libraries function, GetInt.

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Int, let's call it n, equals GetInt.

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And now I'm going to do a bit
of analysis on that integer.

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Somewhat arbitrarily, but with this
new construct known as a switch.

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Switch on the value of n as follows.

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>> In the case that n equals 1, or in the
case that n equals 2, or in the case

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that n equals 3, go ahead and
execute this line of code.

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Printf you picked a small int, break.

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Now, I need to implement the equivalent
of an ELT simple by

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enumerating some additional cases.

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>> In the case that n equals 4, or in the
case that n equals 5, or in the case

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that n equals 6, or in the case that n
equals 7, go ahead and print out you

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picked a medium Int.

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Break.

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Now in the case the user picked
a large number, let's

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detect that as follows.

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>> In the case that the user picked eight
or in the case that the user pick

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nine, or in the case that the user pick
10, go ahead and print out you

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picked a large Int.

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Break.

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ELT, if a user did not pick a number
that falls into any of these 10 cases,

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let's have some default behavior.

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Which in this case will be as follows.

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>> Default, Printf, you picked
an invalid Int.

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Break.

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Now, if I save this file compile
it with make switch.

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Run it with .slash switch.

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Let's do a couple of sanity checks.

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I'll pick an Int of 1.

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And ID picked a small int.

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>> Let's now do .slash switch.

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And type in say, negative 1.

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And ID picked an invalid int.

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At the end of the day, the switch
construct does not enable you to do

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anything that you couldn't already do
with the more familiar if, else if,

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else construct.

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But if you have a finite list of values
that you're checking for, a

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switch statement may very
well make your code more

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explicit, or more readable.

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