What is anonymous
method in C#?
A method without a name is called as
an anonymous method is, the delegate operator creates an anonymous method that
can be converted to a delegate type.
What is use of
anonymous methods in C#?
- You can use an anonymous method to
create an anonymous function with unnamed inline code.
- C# 2.0 introduced the concept of
anonymous methods to write unnamed inline statement blocks that can be executed
in a delegate invocation.
How to create and
use anonymous method?
An anonymous method behaves like a
regular method and allows us to write inline code in place of explicitly named
methods.
Code example
//declare delegate
delegate void displayFullName(string fname, string mName, string lName);
//instantiate delegate with anonymous method
displayFullName fullName = delegate (string fname, string mName, string lName) {
Console.WriteLine("Full name: " + fname + " " + mName + " " + lName);
};
//anonymous method with generic action delegate
Action<string, string, string> userFullName = delegate (string fname, string mName, string lName)
{
Console.WriteLine("User full name: " + fname + " " + mName + " " + lName);
};
What is anonymous
function in C#?
An anonymous function is an
"inline" statement or expression that can be used wherever a delegate
type is expected.
You can use it to initialize a named
delegate or pass it instead of a named delegate type as a method parameter.
You can use a lambda expression or an
anonymous method to create an anonymous function. We recommend using lambda
expressions as they provide more concise and expressive way to write inline
code.
Reference…https://docs.microsoft.com/
How to use anonymous
function in C#?
Anonymous function code examples using,
- Delegate with named method,
- Lambda expression
- Delegate with anonymous method
- Built-in delegates (Func & Action
delegates)
delegate void SampleDelegate(string x);
public class
AnonymousFunctions
{
static void
DisplayData(string x)
{
Console.WriteLine("Data is :" +
x);
}
static void
AnonymousSamples()
{
//
initialization with a named method.
SampleDelegate testNamed = new SampleDelegate(DisplayData);
// C#
2.0: A delegate can be initialized with
// inline
code, called an "anonymous method." This
//
method takes a string as an input parameter.
SampleDelegate TestAnMethod = delegate (string s) {
Console.WriteLine(s); };
// C#
3.0. A delegate initialization with a lambda expression.
//
The lambda also takes a string
// as
an input parameter (x). The type of x is inferred by the compiler.
SampleDelegate TestLambdaExp = (x)
=> { Console.WriteLine(x); };
//Anonymous
function with action generic delegate
Action<string> TestDelGeneric = (s)
=> { Console.WriteLine(s); };
//
Anonymous function with action delegate without paremeters.
Action TestDelActGen = () => {
Console.WriteLine("Codechef4U
samples"); };
//Anonymous
Function with func generic delegate, first 2
//
parameters are input, and last parameter is result
Func<string, string, string> GetCombinedString =
(x, y) => { return x+ " " + y; };
//Anonymous
Function with predicate generic delegate
Predicate<string> isValidSurName = (x)
=> { return x != null && x.Length >2 ? true : false;
};
//
Invoke the delegates.
DisplayData("The named method call using delegate .");
TestAnMethod("The anonymous method call.");
TestLambdaExp("The lambda call.");
TestDelGeneric("The action generic delegate .");
TestDelActGen();
Console.WriteLine("Full name is: "+
GetCombinedString("Aditya", "Kendre"));
Console.WriteLine("Is valid name :" +
isValidSurName("Kendre"));
}
}
What is Anonymous
Type in C#?
Anonymous types are easy way to
encapsulate a set of read-only properties into a single object without having
to explicitly define a type first.
In simple language anonymous type is a
class without name containing only read-only public properties.
Note:
- The type name is generated by the
compiler and is not available at the source code level. The type of each
property is inferred by the compiler.
- If you do not specify member names in
the anonymous type, the compiler gives the anonymous type members the same name
as the property being used to initialize them.
How to create and
use anonymous types in C#?
The following first example shows an
anonymous type that is initialized with two properties named Id and Name.
Following 2nd example Anonymous
type “ITDepartment” created with LINQ query
select clause, first parameter is not named but used inferred anonymous type
member(compiler gives name of department id) name and another parameter is
named “depName”.
Example:
public void ExmployeeData()
{
var Departments = GetAllDepartments();
//1. anonymous type “Employee” with properties named Id and Name.
var Employee = new { Id="sk14",Name = "Shourya" };
//2. anonymous type "ITDepartment" with LINQ query filter
var ITDepartment = from dep in Departments
where dep.Name == "IT"
select new {dep.Id, DepName = dep.Name };
//how to use it?
Console.WriteLine("Employee Id :" + Employee.Id);
Console.WriteLine("Employee Id :" + Employee.Name);
Console.WriteLine("Employee Department Name :" + ITDepartment.FirstOrDefault().DepName);
}
Sample class and method to
create in memory department collection.
public class Department
{
public int
Id { get;
set; }
public string Name { get; set;
}
}
public List<Department> GetAllDepartments()
{
var departments = new List<Department>();
var ITDepartment = new Department
{
Id = 1,
Name = "IT"
};
var AccountDepartment = new Department
{
Id = 2,
Name = "Account"
};
departments.Add(ITDepartment);
departments.Add(AccountDepartment);
return departments;
}
How
to return anonymous type with
Web API?
In follwing code example web method returns anonymous type "Employee"
[HttpGet]
[Route("GetEmployeeData")]
public IHttpActionResult GetEmployeeData()
{
//anonymous type Employee with properties named Id and Name.
var Employee = new { Id = "sk14", Name = "Shourya" };
// Status Code 200;
return this.Ok(Employee);
}
How to return anonymous
type with method?
//Return anonymous Type as object
public object GetAnonymousData()
{
return new { Id = "sk14", Name = "Shourya" };
}
//Display anonymous Type values from object
public void
DisplayAnonymousData()
{
object refobj = GetAnonymousData();
Type type = refobj.GetType();
PropertyInfo[] fields =
type.GetProperties();
foreach (var field in fields)
{
string name = field.Name;
var firstValue = field.GetValue(refobj, null);
Console.WriteLine("Employee Name " +
firstValue);
}
}