# How to Program in C# - Methods (E06)

## Метаданные

- **Канал:** Brackeys
- **YouTube:** https://www.youtube.com/watch?v=bPQx0paXrbw
- **Источник:** https://ekstraktznaniy.ru/video/22681

## Транскрипт

### Segment 1 (00:00 - 05:00) []

- So we've learned how to use variables, loops, and arrays to create different behaviour in our code. But so far, everything we've done has been written from top to bottom. For pretty much all of our programmes, we've created a few variables, gathered some input, done something with it and spit out a result. And while you can get a long way with this, programming doesn't start to get really interesting before we're able to reuse code. And this is exactly where methods come in. A method allows us to group together code that performs a specific task. This way we can write the code only once and then use it whenever we need. But first this video is sponsored by Milanote. Milanote is a tool for organising your creative projects into free form visual boards. It can be used for any creative project but it's particularly well suited for the early stages of game development. In fact, Milanote just released a bunch of new updates including support for code snippets, making it easier than ever to collaborate and share ideas for a project with your fellow developers. It's available for both desktop, Android, and iOS, which is very convenient as you never know when the next idea might strike. We actually use Milanote ourselves for a project. So if you want to have a closer look at Milanote in action. Definitely check out that video. Finally Milanote is free. So get organised and start collaborating with your friends now by simply clicking the link in the description. Say we want some code that prints a random number in our console. Well we can create a method that does this. And there are two things that we need to do when working with methods. First we define the method and then we call it. And what does that mean? Well I like to think of a method like a machine. When we define a method, we choose a name and what we would like it to do. Here we are creating the machine and telling it how to behave. In this case, we want to create a machine called PrintNumber and give it some code for displaying a random number. Let's have a look at doing this in C#. So far, we've written all of our code inside of Main. But when we want to define a method, we do this outside. It doesn't matter if it's before or after as long as it's not inside of Main. So to define our method, we write void, followed by the name, in our case PrintNumber, then we open and close two parentheses, and then some curly brackets. And inside the curly brackets, we write what we want our method to do. In this case, we want to create a random number generator, get a random number from it, and write out the result. And that's it for defining our method. But if we run our programme now, nothing would happen because we also need to call our method. Calling a method means telling the code inside to execute. You can think of it like we're turning on the machine. To do this, we choose to place in our code where we would like to call the method. I would like this to run as soon as the programme starts. So I'll do this on the first line inside of Main, here we write the name of the method, followed by some parentheses and a semicolon. And that's it. If we run our programme now, it's going to see that we want to call the PrintNumber method, go inside of that method, execute all the code inside, and the result is that we get a random number. And we can of course choose to call this anywhere and as many times we'd like. I'm just going to call it a few times in a row here. And as you can see, we now get three random numbers by reusing this same piece of code. Now some of you might have noticed that the method we've created here looks a whole lot like Main. That's because Main is also just a method but it's special because we don't need to call it. Main is just always called right when the programme starts. Also note that methods are often referred to as functions. In C#, these two terms are the same. So if you hear me saying function, don't freak out. It's the same. All right, with that explanation, let's try creating some methods for ourselves. So let's imagine that we are creating a speed dating programme where the user gets to meet a bunch of new people. But instead of meeting other humans, which would be pretty boring, let's have the user meet aliens instead. In fact, let's make a method that creates an alien with a random name and age, and have it say "Hi" to the user. So as we learned to create a method we go outside of Main, that would be down here. It's still within the class but outside of Main and here we start by writing void, then the name of our method, in my case I'm going to call it MeetAlien. I'm going to open and close some parentheses and some curly brackets. I'm also going to take this curly bracket here and put it down here, just like I do with if statements, just to make it easier to read. And that's it. We've actually now defined this function but we should of course put some codes inside to have it do something. I'm going to start out by creating a name and an age for our alien and I would like to base this on random numbers. So first off, we need to create a random number generator. So we'll go random, we'll call our generator numberGen and set it equal to a new random. Again, we've done this in previous videos. The syntax for this is still a bit weird so just write after me. And now we can use this number generator to get random numbers. So if we want to create a name for our alien, we can go string name, and we can set it equal to

### Segment 2 (05:00 - 10:00) [5:00]

and I want all my aliens to have a pretty weird name. I want them to be called something like X, dash, and then some kind of random number. So I'm going to do X, dash, and then plus numberGen. Next in order to create a random number between, and I'm just going to put in 10 and then 9,999. That should look like an alien name. Then for the age, I'm going to do pretty much the same thing. I'm going to create an integer called age, and set it equal to a random number, so numberGen. Next between 10 and 500. Let's pretend these aliens get pretty old. And then we can print some of this information to the screen, so we can go Console. WriteLine, "Hi, I'm, and then the name. " Let's do another one, Console. WriteLine, "I'm and then age, years old. " And let's do a third one, "Oh, and I'm an alien. " So I do admit that this method is a bit weird but it should in fact work. The only thing that we need to make sure to do in this case is to add a static keyword in front of our method. Now what do I mean by this? The only thing that we need to do to make this work is go to the top of our method here before the void and add the static keyword. As you can see the main function has this as well. We'll talk about why in the next video where we're diving into classes but for now just make sure to include it or you'll get an error in your code. And that's it for our function definition. Now we can call it wherever we'd like in our code. I'm just going to go to Main here and try calling it here. So let's go ahead and meet an alien right when the programme starts. And if we run this now, we can see that it says, "Hi, I'm X-8203. I'm 154 years old. Oh, and I'm an alien. " Pretty cool. And of course what's happening in our code here, is that we're going to our main function which gets called right at the beginning of our programme. It sees that we want to call MeetAlien, so it goes down here, into our MeetAlien function, and executes all of this code before going back and continuing down. So if you want, we can go ahead and call MeetAlien some more times in order to meet some different aliens. And I'm just going to put some kind of spacing in between here. So Console. WriteLine and I'm just going to put in a few dashes just to clearly separate the two aliens that we're meeting. And if you run this programme again, we can see that we're now meeting two different aliens with a different age and a different name. Awesome! So that's the most basic example of a method. But where methods really start to shine is when we add parameters and return values. But what does that mean exactly? Well so far, our machine has been pretty closed around itself. We can run it. It does some things and that's pretty much it. But imagine if we were able to give the machine some input when we run it that it can then use. A good example of this is if we want to create a method that squares a number. In this case, we probably want to be able to input a number that the machine should then square. This is called a parameter. And it's pretty simple to write. When defining our method, we go inside of the parentheses and write the type, in our case that's an integer, followed by the name of the parameter, I'm just going to call this number, then inside the curly brackets, we can use this as any other variable. In this case, I'm going to calculate the result by multiplying the number with itself. So we've now created a machine that takes in an integer as a parameter. When we then call the method and run the machine, we just pass in whatever number we'd like it to use. Of course it would be cool if the machine could also spit out the result. We call this a return value. In our case, we would like to return the result of our calculation which is an integer. To do this we replace void, which means that we don't want to return anything, with int. Then inside the curly brackets when we've done everything we wanted to do, we can end the method by writing return followed by the value we would like to output. In our case, that is the result. And this allows us when calling the method to get a value back. And we can of course store this in another variable and use it for whatever we'd like. So we're creating a machine called Square that takes in an integer as a parameter, squares it, and outputs the result. Let's have some fun with this in various code. So let's say that we wanted to create a method that multiplies to numbers. Well in this case, we would again go outside of main here and we would type void to create a method. We give it the name which is something like Multiply. Open and close the parentheses and the curly brackets. And if we want this method to multiply to numbers, we need a way to input the two numbers that we would like. So we'll add these as parameters. To do this, we go inside of our parentheses. And here we first put the type of what we want to input. So in this case that would be an integer and I'm just going to call it num one, for number one.

### Segment 3 (10:00 - 15:00) [10:00]

And the cool thing is that we can actually allow ourselves to input more than one value. So if I just write a comma here, we can create another parameter. So this is going to be an integer as one, and I'm going to call it number two. And there we go, and now we can actually do things with these two numbers inside of our method. So in this case, we probably want to calculate the result and store it in a variable. So let's create an integer called result and set it equal to number one multiplied with number two. It's actually that easy. And if you want, we could of course just print out the results. So we could do Console. WriteLine, the result is, and then result. There we go. Of course just like we did earlier, we need to add the static keyword in front of our method here. For now you need to do this to all of your methods. Again, we'll talk about why in the next video. And with that, we have to find our function. And so we can go up to main here and call it. So I'm going to type in Multiply, and then inside of the parentheses we can put in a few numbers. I'm also going to put in the number 3 and 8. I'm also going to do one with 7 and 13, and let's do one with 11 and 5. Cool. And if we now run this, we can see that the result of 3 times 8 is 24, the result of 7 times 13 is 91, and the result of 11 times 5 is 55. Awesome, but right now we're just displaying the result in the console. What if we wanted to multiply two numbers and then use the result to do something? Perhaps we could check if the result is an even number or an uneven number. So to do this, we add a return value. I'm just going to get rid of some of the multiply function codes here, and down here instead of writing a void which means again, return nothing. We write the type of the number that we want to return. In our case that's an integer because we want to return the result variable. Then instead of printing this directly to the console, let's simply write return, result, and then a semicolon. And now up here what we call the multiply function, we can now store this result in the variable. So we can create some kind of integer, we can call it result and set it equal to whatever is outputted from a multiply function. And please note that while I am giving the same name to this variable and this one, you don't have to. You could easily call this one answer or anything else that you would like. I just think it makes sense to call it result. And now we can do things with this. So we can print it out, Console. WriteLine, the result is, and then the result, and we can check if it's an even number. So we can go if, result, and a pretty cool way to check if a number is even or not is to divide by two and see if it adds up. So just to give an example of this, if we divide two by two, that gives a whole number and so two is an even number. The same thing happens if we divide say, eight by two, that is going to be four. Again a whole number and so that number is even. However, if we divide say, three by two, this is going to give one and a half. This means that there is a remainder to this division, and we're getting a decimal number. So this is uneven. And the same thing with five and so on. Again five divided by two is 2. 5, this is also uneven. So we can use this to check if a number is even or not by checking if the remainder of the division is zero. So in this case, the remainder is definitely zero. The same thing here but if we divide three by two, the remainder is. 5 and the same thing if we divide five by two, the remainder is also. 5. To do this in C#, we use the modules operator or the percentage sign. So here we're saying if we divide the result by two, what is the remainder? And we need that remainder to be equal to zero in order for the number to be even. So if that is the case, if this is true. If the remainder of the division is zero, then the number is even. And so we can go Console. WriteLine, result, is an even number If not, so else, then the number is uneven. So Console. WriteLine, result is an uneven number and there we go. If we now run this, we can see that the result of three times eight is 24. That's correct and 24 is indeed an even number. And if we do this again with some other number, let's say three times three, it says here the result is nine and nine is an uneven number. Awesome. So that's the perfect example of how we can create a function that takes in some input. In our case two numbers here, does something with it, and returns a result when simply displayed or we can do different things depending on the result.

### Segment 4 (15:00 - 17:00) [15:00]

Awesome. Now for this week's challenge, I want you to create a method that can count the number of words in a sentence. To do this, the method must take in a string, the sentence. Figure out how many words are in that sentence and return that number as an integer. So as you can see my programme here, asks the user to enter a sentence. I'm just going to put in, "I love programming. " I'm going to hit enter, and it now says that there are three words in that sentence. And indeed there is. "I love programming. " Awesome! Now to do this, we need to know how to get the word count. And we can do that using the dot split method. As you can see, I have an example string here. And the split method is going to split this string in two in all places that has a specific character. So if I go example. Split, I can then open and close parentheses and a semicolon. And then inside here, we can put two apostrophes and this allows us to input a character. In our case, we want to split every time there is a space so I'm just going to put a space here. Now what this effectively does is divide our one string here into an array of strings. In this case, it would be an array of three items. I, love, and programming and because of that, we can simply use the. Length to get the number of elements inside the array and that should be your word count. So good luck and as always my solution is available on the practise forum. That's of course a link for that in the description. That's pretty much it for this video. If you enjoyed it, make sure to subscribe and ring that notification bell so you don't miss the next one. Also don't forget to check out Milanote. Again, it's free and a great way to organise your projects and share your ideas with friends. To get started, sync the encrypted link in the description. On that, thanks for watching and I will see you in the next video. Thanks to all the awesome Patreon supporters who donated in July and a special thanks to Dante_Sam, Lost to Violence, Loved Forever, NiftyliuS, Scott McKee, faisal marafie, Replica Stuios, Leo Lesetre, Nubby Ninja, Jason Uritescu, Piano Sathornlak, bobby reynolds, Donatien Gascoin, Marc-Antoine Girard, Jacob Sanford, Michail Korobov, Naoki Iwasaki, Gregory Pierce, Owen Cooper, TheMightyZeus, Alison the Fierce, Erasmus, I love Brackeys aw, SiriusWolf, Fred Mastro, Hassan Sher, Storm Daniels, and dennis solomon. You guys rock!