Indexer in C#
An indexer allows an object to be indexed such as an array. When you define an indexer for a class, this class behaves similar to a virtual array. You can then access the instance of this class using the array access operator ([ ]).
In other words it simplifies the way we access the collection.
Overloaded Indexer
Indexers can be overloaded. Indexers can also be declared with multiple parameters and each parameter may be a different type. It is not necessary that the indexes have to be integers. C# allows indexes to be of other types, for example, a string.
In other words it simplifies the way we access the collection.
using System; namespace IndexerApplication { class IndexedNames { private string[] namelist = new string[size]; static public int size = 10; public IndexedNames() { for (int i = 0; i < size; i++) namelist[i] = "N. A."; } public string this[int index] { get { string tmp; if( index >= 0 && index <= size-1 ) { tmp = namelist[index]; } else { tmp = ""; } return ( tmp ); } set { if( index >= 0 && index <= size-1 ) { namelist[index] = value; } } } static void Main(string[] args) { IndexedNames names = new IndexedNames(); names[0] = "Zara"; names[1] = "Riz"; names[2] = "Nuha"; names[3] = "Asif"; names[4] = "Davinder"; names[5] = "Sunil"; names[6] = "Rubic"; for ( int i = 0; i < IndexedNames.size; i++ ) { Console.WriteLine(names[i]); } Console.ReadKey(); } } }
Overloaded Indexer
Indexers can be overloaded. Indexers can also be declared with multiple parameters and each parameter may be a different type. It is not necessary that the indexes have to be integers. C# allows indexes to be of other types, for example, a string.
using System; namespace IndexerApplication { class IndexedNames { private string[] namelist = new string[size]; static public int size = 10; public IndexedNames() { for (int i = 0; i < size; i++) { namelist[i] = "N. A."; } } public string this[int index] { get { string tmp; if( index >= 0 && index <= size-1 ) { tmp = namelist[index]; } else { tmp = ""; } return ( tmp ); } set { if( index >= 0 && index <= size-1 ) { namelist[index] = value; } } } public int this[string name] { get { int index = 0; while(index < size) { if (namelist[index] == name) { return index; } index++; } return index; } } static void Main(string[] args) { IndexedNames names = new IndexedNames(); names[0] = "Zara"; names[1] = "Riz"; names[2] = "Nuha"; names[3] = "Asif"; names[4] = "Davinder"; names[5] = "Sunil"; names[6] = "Rubic"; //using the first indexer with int parameter for (int i = 0; i < IndexedNames.size; i++) { Console.WriteLine(names[i]); } //using the second indexer with the string parameter Console.WriteLine(names["Nuha"]); Console.ReadKey(); } } }
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