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>> SPEAKER: Let's implement a program that
prompts the user for an integer

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but continues prompting them
for another integer until

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that integer is positive.

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Well, let's write this, include cs50.h,
include standard io dot h, int

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main[void].

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Now let's actually begin to prompt the
user for this integer while keeping in

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mind that we want to reprompt
them until that

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number is actually positive.

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>> So I'll want some kind of looping
construct, but a loop that executes at

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least once.

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And recall the do-while loop allows
us to do exactly that.

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Let's code this up.

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>> Let's first declare an int-- we'll
call it n-- in which to store the

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user's integer.

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Let's now do the following.

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Printf, please give me a positive int.

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Let's now get that int using
the CS50 library's GetInt

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function, n gets GetInt.

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And now we're done doing something,
but we're going to want to do this

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while n is--

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what?--

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less than 1, if we indeed
want a positive integer.

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>> Let's go ahead now and print out.

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If all is well, thanks
for the positive int,

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semicolon, save the file.

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Let's now compile and run.

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>> Make positive dot slash positive.

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And now I'm being prompted
for a positive int.

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Let me cooperate with 1.

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Thanks for the positive int.

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>> Let's now rerun this program
and not cooperate.

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Please give me a positive int.

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How about negative 1?

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Interesting.

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The program is already reprompted
me for an int.

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>> Let's be slightly more
difficult with 0.

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Still not a positive int, so let's
cooperate and this time

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provide, again, 1.

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Thanks for the positive int.

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>> Now it's important to note that I
declared my variable n on line 6,

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outside of the do-while loop.

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Had I instead declared n inside of my
do-while loop, specifically on, say,

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line 10, where I also get the int from
the user, that int n would have only

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existed within the confines of the curly
braces that are currently on

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line 8 and on line 11.

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>> In other words, n would be scoped to
the inside of that do-while loop.

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But the problem is that we also
want to use n in line 12

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inside of the condition.

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So even though it doesn't look so
pretty, it's very much deliberate that

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n is declared outside
this do-while loop.

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