YouTipCsharp Indexer
# C# Indexer
**Indexer** allows an object to be accessed in a way similar to an array using an index.
When you define an indexer for a class, the class behaves like a **virtual array**. You can access the class's members using the array access operator .
## Syntax
The syntax for a one-dimensional indexer is as follows:
element-type this
{
// get accessor
get
{
// return the value specified by index
}
// set accessor
set
{
// set the value specified by index
}
}
## Purpose of Indexers
The declaration of an indexer's behavior is somewhat similar to that of a property. Like a property, you can use **get** and **set** accessors to define an indexer. However, properties return or set a specific data member, whereas indexers return or set a specific value of an instance of an object. In other words, it breaks an instance's data into smaller parts and indexes each part, getting or setting each part.
Defining a property involves providing a property name. Indexers are defined without a name, but with the **this** keyword, which refers to the object instance. The following example demonstrates this concept:
## Example
using System;
namespace IndexerApplication
{
class IndexedNames
{
private string[] namelist =new string;
static public int size =10;
public IndexedNames()
{
for(int i =0; i =0&& index =0&& index <= size-1)
{
namelist=value;
}
}
}
static void Main(string[] args)
{
IndexedNames names =new IndexedNames();
names="Zara";
names="Riz";
names="Nuha";
names="Asif";
names="Davinder";
names="Sunil";
names="Rubic";
for(int i =0; i < IndexedNames.size; i++)
{
Console.WriteLine(names);
}
Console.ReadKey();
}
}
}
When the above code is compiled and executed, it produces the following result:
ZaraRizNuhaAsifDavinderSunilRubic N. A. N. A. N. A.
## Overloading Indexers
Indexers can be overloaded. Indexers can also be declared with multiple parameters, and each parameter can be of a different type. It is not necessary for indexers to be of integer type. C# allows indexers to be of other types, for example, string type.
The following example demonstrates overloading an indexer:
## Example
using System;
namespace IndexerApplication
{
class IndexedNames
{
private string[] namelist =new string;
static public int size =10;
public IndexedNames()
{
for(int i =0; i =0&& index =0&& index <= size-1)
{
namelist=value;
}
}
}
public int this
{
get
{
int index =0;
while(index < size)
{
if(namelist== name)
{
return index;
}
index++;
}
return index;
}
}
static void Main(string[] args)
{
IndexedNames names =new IndexedNames();
names="Zara";
names="Riz";
names="Nuha";
names="Asif";
names="Davinder";
names="Sunil";
names="Rubic";
// using the first indexer with int parameter
for(int i =0; i < IndexedNames.size; i++)
{
Console.WriteLine(names);
}
// using the second indexer with string parameter
Console.WriteLine(names["Nuha"]);
Console.ReadKey();
}
}
}
When the above code is compiled and executed, it produces the following result:
ZaraRizNuhaAsifDavinderSunilRubic N. A. N. A. N. A.2