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Welcome back. So, Python gets a lot more interesting once we learn how to write code that

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doesn't actually execute or output the same thing every single time that we run it.

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Now, the first way that we'll learn how to add

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some variability into what our code executes,

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is by getting input from the user.

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So, we'll be able to have different outputs from our code even with

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the same program by asking the user for

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some input and then doing something with that input.

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The way that we'll do that is with the naturally named input function.

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So, input asks the user to enter something.

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So, for example, in this code on line one we ask the user to input their name,

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by calling the input function,

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and the input function accepts a prompt as its argument,

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and so here we prompt the user,

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please enter your name.

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Now, the value of this expression of input,

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is going to be whatever the user entered.

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So, if the user enters Steve,

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then the value of this expression is going to be the string Steve.

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The value of input is always going to be a string no matter what the user enters.

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So, if the user for whatever reason enters 500,

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then the value of this expression would be the string 500,

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and now n gets assigned either Steve,

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500 or whatever string the user entered.

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So, when we print out hello n,

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then we print out hello and whatever the user entered.

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So let's run this code and see what we get.

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So, when I hit save and run,

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you'll see that I have this prompt here,

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and it says please enter your name,

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and that's the exact prompt that we passed into input.

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So, if I type in Steve,

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as my name, then you'll see that my code then prints out hello Steve.

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If I save it on my code and I enter something different, so,

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let's say that I entered Paul,

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then my code is going to output Hello Paul.

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I can enter absolutely anything that I want in here.

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So, I can enter 99999 and my code is going to print out Hello 999999.

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So again, input always gives back a string,

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but let's suppose that we wanted a number instead of a string.

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The way that we would do that is by casting or

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calling one of the functions to convert strings to a number.

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So, for example, let's suppose that we wanted to write

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some code that was going to convert a number of seconds,

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into a number of hours and a number of minutes,

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and we want to also compute the remainder

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when we actually divide to get the number of hours and minutes.

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So, here we prompt the user please enter the number of seconds that you want to convert,

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and then we put that into this variable str_seconds.

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The next thing that we do,

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is we cast that variable str_seconds,

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because again input always gives us back a string,

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we cast that to be an integer,

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and we assign that to be total seconds.

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We then compute the number of hours by taking

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total seconds and then doing division without remainder,

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by 3,600 to convert seconds into hours,

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and then we find out how many seconds are still remaining by

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taking the remainder of total seconds when it's divided by 3,600.

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Then we take those seconds that didn't divide evenly into the number of hours,

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and convert them into minutes by again dividing without remainder by 60,

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and then we figure out how many seconds are still remaining at the end of this by taking

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the remainder when we divide seconds still remaining by 60.

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Then in the end we get the number of hours,

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minutes and seconds for whatever number of seconds the user input.

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So, if I save and run my code,

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and then let's suppose that I just want to convert 60 seconds,

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then I'll see that this is zero hours,

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one minute and zero seconds.

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If I convert 6,000 seconds,

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then I'll see that this is one hour and 40 minutes.

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If I convert 999 seconds,

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then I'll see that that's 16 minutes and 39 seconds etc.

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So, again the point of this is,

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we can use whatever the user entered as an integer by

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converting it to an integer by calling

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n function or if we wanted to make it a floating point,

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we might call it the floating point function.

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Now, you might ask what if the user enters something other than an integer?

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So, if we're asked to enter the number of seconds that I want to convert,

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and I type in let's say my name and I run,

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then you'll see that Python wasn't able to

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convert Steve into an integer and so we get a runtime error.

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Now, let's look at a multiple choice question.

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So, this asks, what gets printed when the following statements execute?

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So, let's suppose that we ask the user,

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please enter your age,

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and then the user enters 18.

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So, here n gets assigned to the string 18

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because remember input always gives us back a string.

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It doesn't matter what the user actually entered,

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even if they enter 18,

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then n gets assigned to the string 18,

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and when we print out the type of n,

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then we're going to get that n is a string.

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That's all for now, until next time.