This property is used to get or set the value associated with the specified key in the Dictionary.
Syntax:
public TValue this[TKey key] { get; set; }
Here, key is the Key of the value to get or set.
Property Value: It is the value associated with the specified key. If the specified key is not found, a get operation throws a KeyNotFoundException, and a set operation creates a new element with the specified key.
Exceptions:
- ArgumentNullException: If the key is null.
- KeyNotFoundException: If the property is retrieved and key does not exist in the collection.
Example:
// C# code to get or set the value // associated with the specified key using System;
using System.Collections;
using System.Collections.Generic;
class GFG {
// Driver code
public static void Main()
{
// Creating a Dictionary named myDict
Dictionary< string , string > myDict = new Dictionary< string , string >();
// Adding key/value pairs in myDict
myDict.Add( "Australia" , "Canberra" );
myDict.Add( "Belgium" , "Brussels" );
myDict.Add( "Netherlands" , "Amsterdam" );
myDict.Add( "China" , "Beijing" );
myDict.Add( "Russia" , "Moscow" );
myDict.Add( "India" , "New Delhi" );
// Displaying the key/value pairs in myDict
foreach (KeyValuePair< string , string > k in myDict)
{
Console.WriteLine( "Key = {0}, Value = {1}" ,
k.Key, k.Value);
}
// Displaying the value associated
// with key "Russia"
Console.Write( "\nValue associated with Russia: " );
Console.Write(myDict[ "Russia" ]);
// Setting the value associated with key "Russia"
myDict[ "Russia" ] = "Saint Petersburg" ;
// Displaying the value associated
// with key "Russia"
Console.Write( "\n\nValue associated with Russia After Setting: " );
Console.Write(myDict[ "Russia" ]);
// Displaying the value associated
// with key "India"
Console.Write( "\n\nValue associated with India: " );
Console.Write(myDict[ "India" ]);
// Setting the value associated with key "India"
myDict[ "India" ] = "Mumbai" ;
// Displaying the value associated
// with key "India"
Console.Write( "\n\nValue associated with India After Setting: " );
Console.Write(myDict[ "India" ]);
Console.WriteLine( "\n" );
// Displaying the key/value pairs in myDict
foreach (KeyValuePair< string , string > k1 in myDict)
{
Console.WriteLine( "Key = {0}, Value = {1}" ,
k1.Key, k1.Value);
}
}
} |
Output:
Key = Australia, Value = Canberra Key = Belgium, Value = Brussels Key = Netherlands, Value = Amsterdam Key = China, Value = Beijing Key = Russia, Value = Moscow Key = India, Value = New Delhi Value associated with Russia: Moscow Value associated with Russia After Setting: Saint Petersburg Value associated with India: New Delhi Value associated with India After Setting: Mumbai Key = Australia, Value = Canberra Key = Belgium, Value = Brussels Key = Netherlands, Value = Amsterdam Key = China, Value = Beijing Key = Russia, Value = Saint Petersburg Key = India, Value = Mumbai
Reference: