OrderedDictionary.Add(Object, Object) method is used to add an entry with the specified key and value into the OrderedDictionary collection with the lowest available index.
Syntax:
public void Add (object key, object value);
Parameters:
key : The key of the entry to add.
value : The value of the entry to add. This value can be null.
Exceptions :
- NotSupportedException : If the OrderedDictionary collection is read-only.
- ArgumentException : If an element with the same key already exists in the OrderedDictionary collection.
Below given are some examples to understand the implementation in a better way:
Example 1:
// C# code to add key and value // into OrderedDictionary using System;
using System.Collections;
using System.Collections.Specialized;
class GFG {
// Driver method
public static void Main()
{
// Creating a orderedDictionary named myDict
OrderedDictionary myDict = new OrderedDictionary();
// Adding key and value in myDict
myDict.Add( "key1" , "value1" );
myDict.Add( "key2" , "value2" );
myDict.Add( "key3" , "value3" );
myDict.Add( "key4" , "value4" );
myDict.Add( "key5" , "value5" );
// Displaying the number of key/value
// pairs in myDict
Console.WriteLine(myDict.Count);
// Displaying the key/value pairs in myDict
foreach (DictionaryEntry de in myDict)
Console.WriteLine(de.Key + " --> " + de.Value);
}
} |
Output:
5 key1 --> value1 key2 --> value2 key3 --> value3 key4 --> value4 key5 --> value5
Example 2:
// C# code to add key and value // into OrderedDictionary using System;
using System.Collections;
using System.Collections.Specialized;
class GFG {
// Driver method
public static void Main()
{
// Creating a orderedDictionary named myDict
OrderedDictionary myDict = new OrderedDictionary();
// Adding key and value in myDict
myDict.Add( "key1" , "value1" );
myDict.Add( "key2" , "value2" );
// This should raise "ArgumentException"
// as an element with the same key already
// exists in the OrderedDictionary collection.
myDict.Add( "key2" , "value3" );
myDict.Add( "key4" , "value4" );
myDict.Add( "key5" , "value5" );
// Displaying the number of key/value
// pairs in myDict
Console.WriteLine(myDict.Count);
// Displaying the key/value pairs in myDict
foreach (DictionaryEntry de in myDict)
Console.WriteLine(de.Key + " --> " + de.Value);
}
} |
Runtime Error:
Unhandled Exception:
System.ArgumentException: Item has already been added. Key in dictionary: ‘key2’ Key being added: ‘key2’
Note: A key cannot be null, but a value can be.
Reference: