Methods are used to define reusable logic and are declared with access modifiers, a return type, name, and optional parameters. There are two types of methods: static methods associated with a class and instance methods associated with an object. Parameters can be passed by value, reference, or as out/ref parameters. Optional and named parameters allow flexibility in how arguments are passed to methods.

1. Methods
Eng Teong Cheah
Microsoft MVP Windows Development

2. Xamarin: the complete mobile lifecycle solution

3. Methods

4. Methods
Methods are used to define logic once and use it at many places, which make
maintenance of program easier.
Syntax of declaring methods”
[Attributes]
access-modifiers return-type methodname( parameters )
{
methodbody
}

5. Methods
Access modifiers can be private, public, protected, internal, protected internal.
- Return type can be any valid date type or void if nothing is returned by method.
- Method name is name of the method.
- Parameters can be any data type. Parameters are optional.
Methods are of two types:
- Static Methods
- Instance methods

6. Static methods
Static Methods are associated with class. Example:
class Program
{
//declaring and using static method
public static void print()
{
Console.WriteLine("printing done");
}
static void Main(string[] args)
{
print();
Console.ReadKey();
}
}

7. Instance methods
Instance methods are associated with instance. Example:
class Program
{
//declaring and using instance method
public void print()
{
Console.WriteLine("printing done");
}
static void Main(string[] args)
{
Program p = new Program();
p.print();
Console.ReadKey();
}
}

8. Methods parameters
There are four types of method parameters:
- Value parameters
Passing parameter by value
- Reference parameters
Passing parameter by reference
- Out parameters
Out parameter is used when we want multiple values output from single method and
don’t know the initialization value of input parameter.
- Parameters arrays
Passing array as parameter

9. Value parameters
Passing parameter by value:
class Program
{
//passing parameter by value
public void increment(int i)
{
++i;
}
static void Main(string[] args)
{
Program p = new Program();
int j = 10;
p.increment(j);
Console.WriteLine(j);
Console.ReadKey();
}
}
Result :-
10

10. Reference parameters
Keyword ref is use for passing the value type by reference.
Passing parameter by reference:
class Program
{
//passing parameter by reference
public void increment(ref int i)
{
++i;
}
static void Main(string[] args)
{
Program p = new Program();
int j = 10;
p.increment(ref j);
Console.WriteLine(j);
Console.ReadKey();
}
}

11. Out parameters
Out parameters is used when we want multiple values output from single method and
don’t know the initialization value of input parameter.
class Program
{
//passing out parameter
public int initialize(out int i)
{
i = 10;
int j = i + 1;
return j;
}
static void Main(string[] args)
{
Program p = new Program();
int j;
int increasedvalue = p.initialize(out j);
Console.WriteLine("value and incremented value is {0} {1}", j, increasedvalue);
Console.ReadKey();
}
}

12. Parameter arrays
Passing array as parameter:class Program
{
//passing array as parameter
public int[] initialize(int[] arr)
{
for (int i = 0; i < arr.Length - 1; i++)
{
arr[i] = i;
}
return arr;
}
static void Main(string[] args)
{
Program p = new Program();
int[] arr = new int[10];
// passing array as parameter;
p.initialize(arr);
for (int i = 0; i < arr.Length - 1; i++)
{
Console.WriteLine(arr[i]);
}
Console.ReadKey();
}
}

13. Optional and Named parameters
Using Optional parameters:
class Program
{
// length and breadth are optional parameter
public void print(int pages, int length = 100, int breadth = 40)
{
Console.WriteLine("length, breadth, no of pages {0} {1} {2}", length, breadth, pages);
}
static void Main(string[] args)
{
Program p = new Program();
p.print(10);
Console.ReadKey();
}
}

14. Optional and Named parameters
Using Named parameters:
class Program
{
public void print(int pages, int length, int breadth)
{
Console.WriteLine("length, breadth, no of pages {0} {1} {2}", length, breadth, pages);
}
static void Main(string[] args)
{
Program p = new Program();
// passing parameters by name
p.print(length: 10, breadth: 16, pages: 10);
Console.ReadKey();
}
}

15. Demo

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