Indexer in c#

Malaravan Anthony

12y1.4kVisual Basic .NET

What is the use of indexer in c# and where it is used in realtime ?

3 Replies

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Palle Technologies12y ago
IN C# indexers are used for accessing private arrays , and also can be used for modifying private arrays data secured using familiar array kind of syntax . For example assume we have a student class , in which we want to store 3 subject marks of a student . As per indian universities the usually the maximum subject marks cannot exceed 100 . For this situation we can write the following code using Indexers .

public class Test
{
public static void Main(string[] args)
{
Student os = new Student();
os[2] = 567;//this marks are not valid and cannot be updated.
os[1] = 85;//this marks are valid and can be updated .
}
}
public class Student
{
private int[] marks = new int[] { 56, 67, 80, 34 };
public int this[int i]
{
get { return marks[i]; }
set
{
if(value>=0&&value<=100)
marks[i] = value;//modify data only when marks is between 0 to 100.
}
}
}
For more info on C# indexers or C# properties you can read properties in C# . Let me know if you have any other questions .
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Abhay Shanker12y ago
An indexer provides array-like syntax. It allows a type to be accessed the same way as an array. Properties such as indexers often access a backing store. We often accept an int parameter and access a backing array.

Check below link for detail
http://msdn.microsoft.com/en-us/library/6x16t2tx.aspx
http://www.c-sharpcorner.com/UploadFile/senthurganesh/109172007050741AM/1.aspx
http://questpond.blog.com/2013/04/16/c-csharp-interview-questions-and-answers-what-are-indexers-in-net/
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Vulpes12y ago
An indexer provides the programmer with a natural way to access elements in a class or struct which wraps an array, list or dictionary object.

In effect, you can access the elements of the collection from within the class or struct wrapper just like you would if you were accessing them directly.

For this reason, indexers are commonplace in any such class or struct and there are many examples in the .NET framework itself.

For example, a string can be thought of as an array of chars and the string indexer enables you to access the char at a specific index:

string s = "indexer";
char c = s[2]; // 'd'

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