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:
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