1-variables.md

marp	paginate	title
true	true	Programming 1. Variables

1. Variables

About C#

• C# is a general-purpose object-oriented language
• Created by Microsoft in 2000 as a competitor for Java
• Syntax
  • Pretty much everything will be inside a class
  • Curly brackets { and } mark the bodies of statements
    • Namespaces, classes, functions...
• Semicolon at the end of most statements
  • VS code tells if it's missing!

C# syntax example

using System;

namespace MyAwesomeProgram
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
        }
    }
}

• In Unity, we don't (necessarily) have to deal with namespaces.

Variable declaration

int number = 1;

1. Modifiers (not necessary)
2. Type declaration
3. Variable name
4. Initial value (not necessary) after =
5. Line ending with ;

Commenting

• one line

  // one line comment

• multiline

  /* this is a
  multi-line
  comment */

• Comments are not executed
• Use to
  1. explain your intent
  2. comment out actual code for testing and debugging

The most important variable types

• bool: truth value (true / false)

bool booleanValue = true;

• int: whole number

int wholeNumberValue = 3;

• double & float: decimal number (double = double precision)

float numberValue = 3.0f;

• string: text field

string text = "text is here";

Modifiers

• A common modifier to add in front of a variable is const, short for constant
• If we know that a value of a variable is never going to change during the execution of the script, we can set it to const:

  const string text = "I never change!";

• Other modifiers include access modifiers.

Unity Console

• Console Window
  • Error messages
  • Debug messages
• Debug.Log(textVariable)
  • Use it to print stuff into the console
  • As the name suggests, it's used for debugging
  • You can print other variable types as well, not only strings!
• Debug.LogWarning()
• Debug.LogError()

---

Basic arithmetic operations

• + (addition)
• - (subtraction)
• * (multiplication)
• / (division)

Extra: Modulo operator

• %
  • modulo operator (remainder)
  • great for looping a range

Exercise 1: Trying out variables

• Create a new Unity project for simple programming exercises.

• Create a new C# script component inside an empty GameObject.

• Declare two variables a and b with the type double.

• In the Start() function, print to console four operations: the sum, difference, fraction and product.

• What happens if either of them is equal to zero?

Reading

Microsoft's own C# Reference is a great way to dive deeper into the language.

Some basics covering the syntax in C# are covered here:

• Sepeli ry: C# (In Finnish)
• https://www.tutorialspoint.com/csharp/index.html
• https://www.w3schools.com/cs/default.asp