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In the last lesson,

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we saw a very simple form of a function that allows for an input.

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Now in this lesson,

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I want to take it even further and I want to create a function that allows for

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multiple inputs.

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So let's comment out of the previous line of code and let's create a new comment,

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functions with more than one input.

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And I'm going to create a new function called greet_with.

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And in this case, it's going to take two parameters.

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It's going to be name and location. If you remember,

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this is how we added a parameter previously. Now, as a challenge,

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I want you to quickly think about how you might add two parameters,

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one's called name and one's called location, into this function

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declaration. Pause the video, have a brief think,

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and then we'll go through it together. All right.

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So we know that if we wanted to add one parameter name,

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then this is how we would do it. We would just add it inside the parentheses.

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Now, if we wanted to have more than one parameter,

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all we have to do is just add a comma and then add the second parameter which we

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said was going to be called location.

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So now this particular function is going to take two inputs,

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the name and the location. And then inside this function,

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we're going to use the name to print something like hello name,

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and then we're going to print and ask them,

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what is it like in their particular location.

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See if you can modify this to use the actual parameters and to replace them with

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print statements so that we use these parameters inside of our function.

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Pause the video now and give that a go. All right.

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So essentially we want to create a print statement here and print statements

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print strings so we have to add some quotation marks around that text.

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And then finally,

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I'm going to use a fstring to replace this parameter name inside this string so

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that the data that gets passed in gets replaced here, and it says,

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hello, whatever their name is.

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And then I'm just going to do the same thing over here

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and notice that with replit and a lot of other text editors,

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you can simply highlight a word or highlight or a sentence,

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and then use the open curly brace to actually add brace around both sides of the

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word. And you'll notice that I did the same thing with the quotation marks.

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So it highlight the whole sentence and then hit the double-quote key

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and it will keep adding quotes around both sides of your highlight.

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But I only actually need one.

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So that is our function completed.

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And now it means I can call this function by calling greet_with,

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and it's going to prompt me to add both of these inputs.

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And the first piece of data is going to be the name

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and you can see it's giving you a hint by underlining the name of the parameter

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here. And let's put Jack Bauer

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and then we can add the second piece of data and separate it with a comma.

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And now you can see this underline has moved to the location parameter.

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So again, a hint as to what kind of data it wants.

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So let's say that Jack Bauer is nowhere. Now,

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if we go ahead and run this code,

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then you'll see that it's going to print hello and replace name with Jack Bauer.

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And then what is it like in nowhere? So no

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where gets replaced with this location.

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So that means that you can now put in as many pieces of inputs as you want and

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modify the functionality of your function to make your function do different

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things each time. Now here's a question.

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What happens if I call the same function greet_with,

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but I switch the order of the data that I give it.

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So let's say the first piece of data I give it is nowhere,

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and then the second piece of data is Jack Bauer.

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So we've just switched the order of these pieces of data. Now,

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what do you expect to happen?

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Pause for a moment and have a think about what you expect to be printed in here

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and then continue. All right,

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so let's click run and you can see that it's now complete nonsense.

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Hello, nowhere. What is it like in Jack Bauer? And what actually happened here

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is it takes the position of the data, looks at both of these arguments,

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and the first argument gets assigned to the first parameter

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the second argument gets assigned at the second parameter. So in this case,

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when it's actually gone in here, name is now equal to nowhere,

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which is why this line printed thi.sAand Jack Bauer is now assigned to location

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which is why it printed this second line like so. And in Python programming,

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this is called a positional argument because when we call the function,

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we haven't specified anywhere which particular parameter we want to associate

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these pieces of data with. So it's just gone and looked at the position.

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Now this is the default way of calling functions, because on one hand,

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when you're typing out the code,

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you get the hints here as to which piece of data you need to enter.

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But also you can refer to the function and look at the order of the parameters.

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Even if we had more inputs, let's say in this case, we had a,

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b and c, and we put the arguments one, two and three,

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then it means that our variables that gets created

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will be a equals one,

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b equals two and c equals three.

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Now, if we switch around the order of the arguments in the function call,

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now what will happen is a is going to be equal to the first argument.

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So a is now equal to three, b as equal to the second argument and c is equal to

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the third argument. So it might be doing slightly unpredictable things in here.

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So whenever you're creating code and you're using these positional arguments,

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and you're just inserting the data one by one like this,

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and it does something completely unexpected,

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then be sure to check your positioning and to make sure that it matches with the

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position of the parameters. Now,

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what if you wanted to be more clear when you actually call the function

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so you don't ever encounter this problem? Well,

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you could use something called keyword arguments instead. So now,

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instead of just adding the arguments into the function call like this,

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we can actually add each of the parameter names and an equal sign to say that

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the first parameter a

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should be equal to one, b should be equal to two and c equals to three.

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And now when we actually change the order around,

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it doesn't matter how we order it,

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it still going to abide by these bindings. So c

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will still be three and a will still be one. 

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As a challenge, I want you to take this previous function,

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greet_with_name and location,

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and I want you to call this function down here, but this time,

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instead of using positional arguments, I want you to use keyword arguments.

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So pause the video and try and give that a go.

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All right. So when we call the function, we still use the name.

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So it's greet_with, so everything up to the first parentheses is the name.

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And then we add in each of these parameter names,

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and then we add an equal sign and finally, we give it the actual value.

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So let's say Angela,

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and then the location is going to be equal to London.

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Now, when I hit run,

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you can see it does pretty much the same as before. It puts Angela into the name,

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London into location. But this time if I switch the order around it

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no longer matters. And when I hit run again,

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you can see it does exactly the same thing,

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because it now knows which argument is associated with which parameter.

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So this can make your code less error prone

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but it does make each line of code longer.

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I recommend using your judgment to figure out when you want to use which type of

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argument and depending on the need, you can pick between these two.

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Now in the next lesson, I've got a coding exercise for you to put into practice

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everything that you've learned so far.

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Head over there when you're ready and let's give it a go.