C#

• C# is an object-oriented language developed by Microsoft especially for platform games and apps.
• Currently one of the two options for Unity scripts. The other one is Javascript.
• Strongly typed, almost every type is a class, functional (has anonymous functions).
• No explicit pointers but many things are pointers.
• Very similar to C++ and Java. A lot of common syntax.

Data Types

• Simple C-style data types are available: int, float, double, char, bool, etc. OOP-style function calls can be made on them.
• int i;
  i.ToString()
• Everything else is either a class, a struct, or an array of one of these data types.
• Function prototypes (or signatures) can be grouped in an interface.
• Value types (simple, struct) vs reference types (classes).

C# Classes

• Single inheritance from another base class.
• Attributes and methods can public, protected, or private (or internal).
• Static attributes or methods belong to the class. All the others are instance-based.
• The function Main() must be static if present in a class.
• Classes can inherit from multiple interfaces.
• Multiple constructors allowed.
• Syntax similar to C++.

Classes in C#

public class Manager: GameObject { 
    public int level;
    public Manager() {
        level = 0;
    }
    ...
} 
Manager m = new Manager();

Structs

• Similar to C++.
• Similar to classes: they have attributes, methods, constructors.
• They don't inherit from other structs or classes.
• No user-defined default constructors. A struct constructor must provide values for every field.

Example

public struct CoOrds { 
    public int x, y; 
    // cannot initialize them here 
    // unless they are static or in Unity
    public CoOrds(int p1, int p2) { 
        x = p1; 
        y = p2; 
    } 
} 

Arrays

• No static size for arrays. They must be initialized with the new operator.
• int[] a1 = new int[5];
• int[] a2 = new int[] { 1, 3, 5, 7, 9 };
• int[] a3 = { 1, 2, 3, 4, 5, 6 };
• Multidimensional arrays:
• int[,] ma1 = new int[2, 3];
• int[,] ma2 = { { 1, 2, 3 }, { 4, 5, 6 } };
• Access: ma[i, j];

Loops

• Usual C++ loops: do, for, while.
• foreach loop: iterates over an array or some other collection.

foreach (int element in a1) {
    System.Console.WriteLine(element); 
} 
for (int i=0; i < a1.Length; i++) {
    element = a1[i];
    System.Console.WriteLine(element); 
} 

Exception Handling

• try { } - enclose a piece of code that might have an error.
• catch(ExceptionType e) { } - action to be taken in case the specified error happens.
• throw new ExceptionType(); - generate an exception of this type that can be matched to a catch.
• ExceptionType must be derived from System.Exception .
• throw; - with no argument inside a catch, throws an exception of the same type.

Example

object o2 = null; 
try 
{ 
    int i2 = (int) o2; // Error 
}
catch (InvalidCastException e) { 
    // take some action
}

Function Parameters

• Unless specified otherwise, a parameter is a value parameter (except that objects are references).
• A parameter preceded by ref is a reference parameter. It must be initialized before the function is called.
• A parameter preceded by out is an output reference parameter. It must be initialized inside the function.

Ref Example

class RefExample 
{
    static void Method(ref int i) { 
        i = i + 44; 
    } 
    static void Main() { 
        int val = 1; 
        Method(ref val); 
        Console.WriteLine(val); 
        // Output: 45 
    } 
}

Out Example

class OutExample {
    static
    void Method(out int i) { 
        i = 44; 
    } 
    static void Main() { 
        int val; 
        Method(out val); 
        Console.WriteLine(val); 
        // Output: 44 
    } 
}