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So this is something that I had to build out for an application recently and so I thought it would be a good idea to include it as an exercise because if you've never done this kind of thing before then the solution might not be the most intuitive. So what we're looking to do is to have a function so that when it's called if it's passed in a gross value. So say this is going to be the sale price and the sale price is 3.21 cents. The output of this function should be 3. something like 99 or 95. We also want the ability to have the flexibility to say if it's going to be 99 or 95 or something else you may want it to just be flat 3 dollars and so this is going to be an exercise where you can do that.
Now I want to walk through what type of solution before actually getting the solution I want to give you one hint on the solution and that is showing you how you should be able to call this function because I put in a little bit of a twist on it. And so I want to be able to call the function like this where I say pretty price and then like you saw before I could pass in something like 3 dollars and 20 cents and then 99 and the output of this should be something like 3 dollars and 99 cents. But now I want it to be a little bit more flexible so that if I say 3 dollars and 20 cents and then pass in a decimal then I want the output to be exactly the same.
The reason why I'm doing this is, imagine that you're building out some kind of code library that other developers were going to use, and sometimes they have a whole number that they would pass in and other times they have a decimal in this scenario. I think it makes sense to have both of these working. So that is the set of instructions so I recommend that now you pause the video and then come back and you can watch me as I go through my own personal solution.
So welcome back, if you went through that. I'm going to get rid of the comments here and start building this out. So I'm going to create a function called pretty_price and it's going to take two arguments. One is going to be the gross_price so this would be whatever that sale price is. And then another one's going to be the extensions so this will be something like 99, 95, or whatever you want the decimal extension to be. Now let's first talk about the easiest way to get this solved, I'm not going to worry about that conversion between a whole number of 95 and a 0.95 decimal.
Let's first simply build out the basic functionality, so I know that I need to convert that gross price. So if I have something like this, I know that gross price needs to be able to be converted to 3 and then I can tack on whatever that extension is. So let's see in the python repl the easiest way of doing this, so let's start that up. And so you can see if we go with our value here. So let's say it's going to be 3.23 cents and I only want to get three back. Well, the way we can do that is we can cast this value to int.
So we have a function in python called int and if I pass x to it you can see that it returns the integer value which means it strips out all of the decimals.
So if you went through the solution and you tried to do something where you saw the decimal and then you checked to see what the value was and then you tried something like floor or ceiling or anything like that, you really don't even need to do that in this case. All you have to worry about is stripping it away and converting it into an integer and then it's going to work. So casting that int is going to be all that we need to do to get the basic functionality working. So here I can say return and then int gross_price and then let's just add that to the extension. So now if I come down here and call this. So let's say pretty price and pass in 3.50 and then for the sake of our first example we are saying 0.95 cents, just like that let's print this out and see if this is working. So let's run it Python pretty price and that worked perfectly.
So we have now a pretty price generator and it works very nicely whenever a decimal is passed like we have right here. Now let's see what we need to do in order to make this work for whole numbers because if we try this with whole numbers we change this to 95 and said 95 cents if we try this now then you're going to see that we end up with 98 which is definitely not what we're looking for.
So what I can do here is I can perform a check. So inside of the function itself, I can add a conditional and there is a very helpful method here because what I need to do is I need to check to see if that second argument if the extension is a decimal or if it's an integer. And so what I can do is I can check and say if isinstance this is the function, this is something provided by python. So I can say if isinstance(extension, int) then I want to perform some other task. So what this is saying is I'm checking to see is this extension an instance of integer, so is it an integer is all it's really saying.
Then what I want to do is I want to reassign extension. So I'm gonna say extension = extension * 0.01. And so what this is going to allow us to do is I can work with the same variable name. Notice how I didn't have to make a single change here on line 5 in that return statement, I'm simply updating the value of extension.
So now let's test this out and see if it's working. And there we go, both of those are working perfectly.
So you can see that our API is much more flexible with our function now. So now if you're working with a program that has decimals that are coming in for that extension you can pass in the decimal if you have whole numbers coming in then you can pass in a whole number and it will work nicely. So this is something that you could use in your own real-life e-commerce projects and I know that that is the case because I have pretty much this identical code inside of a project that I needed to add this functionality to. So great job if you went through that.