C# For Beginners - Lesson 1: Hello, World!
Tags: csharp, dotnet, beginners, tutorial
Published: 2021-07-12 15:14:32

> At the end of this lesson, you should be able to answer the following:
> 
> * What is a statement?
> * How do I display a message on the screen using C\#?

---

Let's make our program print a message. We're going to print out "Hello, World!" to the console. 

A console \(also known as terminal\) is a text-only display or environment that enables us to interact with the computer.

> **Did you know?**
> 
> The ["Hello, World!" program](https://en.wikipedia.org/wiki/%22Hello,_World!%22_program) is the traditional first program for programming languages. It is often the first program written by people who are learning to code.

To make our C\# program print a message, we'll use a command called `Console.WriteLine()`.

The message you want to display goes inside the round brackets `()`. We also need to put the message inside double quotes, like this: 

**`"Hello, World!"`**

In the code box on your notebook, type the following:

```csharp
Console.WriteLine("Hello, World!");
```

This line of instruction is called a _statement_. C\# programs are made up of statements. 

Statements end with a semicolon \(`;`\). Think of a statement like a sentence - the semicolon is equivalent to the full stop or period. 

If there were no full stops, the reader \(in our case, the C\# compiler\) will have trouble understanding us, since it doesn't know where our sentences begin and end.

Next, run the program by clicking on the Execute button on the code box.

![The location of the Execute button](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/imlefcbfurepubz9mnoq.png) 

The output of the program will be shown at the bottom of the code box.

![Hello, World!](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/x9g68ozph836z2vtsyqy.png) 

**Congratulations**! You have written and run your first C\# program.

Let's display another message. Write `I'm learning C#!` to the console.

After the first `Console.WriteLine()`, press Enter to go to a new line and type the next statement.

```csharp
Console.WriteLine("I'm learning C#!");
```

The full program should look like this:

```csharp
Console.WriteLine("Hello, World!");
Console.WriteLine("I'm learning C#!");
```

Run the program again by clicking the Execute button.

Your output should look like this:

![The output of your second program](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/pzstwm40q9gw1o2etsx8.png) 

As you may have noticed, statements run **in sequence**. If you placed `I'm learning C#!` before the `Hello World!` statement, the output would be different.

> **Tip**
>
> You may have notice a box popping up while typing. This feature is part of [**IntelliSense**](https://code.visualstudio.com/docs/editor/intellisense), a helpful tool for writing code. It provides hints, suggestions, and documentation for your code.

![IntelliSense at work](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/9m0xd0lb61d9gy3vbnpn.png)
 
---

> **Question**
> 
> What happens when you remove the semicolon from the end of the statements? Will the program run?
> 
```csharp
Console.WriteLine("Hello World")
Console.WriteLine("I'm learning C#!")
```

---

> **Question**
> 
> Can you spot the error in this program? \(If you're stuck, copy and paste this to the code box. The squiggly red lines will show you where the error is!\)

```csharp
Console.WriteLine(Hello World!);
```

---

> **Challenges**
> 
> 1. Introduce yourself to the computer! Display the message **`Hi! My name is <NAME>`**. Replace **`<NAME>`** with your name, of course.
> 2. Print out your favourite haiku \(Japanese poem\) on the console. If you don't have one, use one of the examples [here](https://examples.yourdictionary.com/examples-of-haiku-poems.html). Each line of the haiku should be printed on its own line.