public struct Vector64

{

public Vector64(long x, long y)

{

X = x; Y = y;

}

public long X { get; } public long Y { get; }

public override string ToString() => $"{{{X}, {Y}}}";

}

Example

var vector1 = new Vector32(15, 39); var vector2 = new Vector32(87, 64);

Console.WriteLine(vector1 == vector2); // false

Console.WriteLine(vector1 != vector2); // true

Console.WriteLine(vector1 + vector2); // {102, 103}

Console.WriteLine(vector1 - vector2); // {-72, -25}

Section 52.28: char

A char is single letter stored inside a variable. It is built-in value type which takes two bytes of memory space. It represents System.Char data type found in mscorlib.dll which is implicitly referenced by every C# project when you create them.

There are multiple ways to do this.

1.char c = 'c';

2.char c = '\u0063'; //Unicode

3.char c = '\x0063'; //Hex

4.char c = (char)99;//Integral

A char can be implicitly converted to ushort, int, uint, long, ulong, float, double, or decimal and it will return the integer value of that char.

ushort u = c;

returns 99 etc.

However, there are no implicit conversions from other types to char. Instead you must cast them.

ushort u = 99; char c = (char)u;

Section 52.29: params

params allows a method parameter to receive a variable number of arguments, i.e. zero, one or multiple arguments are allowed for that parameter.

int i = 0; while (i++ < 5)

{

Console.WriteLine("While is on loop number {0}.", i);

}

Output:

"While is on loop number 1." "While is on loop number 2." "While is on loop number 3." "While is on loop number 4." "While is on loop number 5."

Live Demo on .NET Fiddle

A while loop is Entry Controlled, as the condition is checked before the execution of the enclosed code block. This means that the while loop wouldn't execute its statements if the condition is false.

bool a = false;

while (a == true)

{

Console.WriteLine("This will never be printed.");

}

Giving a while condition without provisioning it to become false at some point will result in an infinite or endless loop. As far as possible, this should be avoided, however, there may be some exceptional circumstances when you need this.

You can create such a loop as follows:

while (true)

{

//...

}

Note that the C# compiler will transform loops such as

while (true)

{

// ...

}

or

for(;;)

{

// ...

}

into

{

:label

// ...

goto label;

}

Note that a while loop may have any condition, no matter how complex, as long as it evaluates to (or returns) a boolean value (bool). It may also contain a function that returns a boolean value (as such a function evaluates to the same type as an expression such as `a==x'). For example,

while (AgriculturalService.MoreCornToPick(myFarm.GetAddress()))

{

myFarm.PickCorn();

}

Section 52.31: null

A variable of a reference type can hold either a valid reference to an instance or a null reference. The null reference is the default value of reference type variables, as well as nullable value types.

null is the keyword that represents a null reference.

As an expression, it can be used to assign the null reference to variables of the aforementioned types:

object a = null; string b = null; int? c = null; List<int> d = null;

Non-nullable value types cannot be assigned a null reference. All the following assignments are invalid:

int a = null; float b = null; decimal c = null;

The null reference should not be confused with valid instances of various types such as:

an empty list (new List<int>())

an empty string ("")

the number zero (0, 0f, 0m)

the null character ( '\0' )

Sometimes, it is meaningful to check if something is either null or an empty/default object. The System.String.IsNullOrEmpty(String) method may be used to check this, or you may implement your own equivalent method.

private void GreetUser(string userName)

{

if (String.IsNullOrEmpty(userName))

{

//The method that called us either sent in an empty string, or they sent us a null reference. Either way, we need to report the problem.

throw new InvalidOperationException("userName may not be null or empty.");

}

else

{

//userName is acceptable.

Console.WriteLine("Hello, " + userName + "!");

}