IDictionary.Add Method

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Adds an element with the provided key and value to the IDictionary object.

Namespace: System.Collections
Assembly: mscorlib (in mscorlib.dll)

Syntax

Sub Add ( _
    key As Object, _
    value As Object _
)
void Add(
    Object key,
    Object value
)

Parameters

Exceptions

Exception Condition
ArgumentNullException

key is nullNothingnullptra null reference (Nothing in Visual Basic).

ArgumentException

An element with the same key already exists in the IDictionary object.

NotSupportedException

The IDictionary is read-only.

-or-

The IDictionary has a fixed size.

Remarks

You can also use the Item property to add new elements by setting the value of a key that does not exist in the dictionary (for example, myCollection["myNonexistentKey"] = myValue). However, if the specified key already exists in the dictionary, setting the Item property overwrites the old value. In contrast, the Add method does not modify existing elements.

Implementations can vary in whether they allow the key to be nullNothingnullptra null reference (Nothing in Visual Basic).

Examples

The following code example demonstrates how to implement the Add method. This code example is part of a larger example provided for the IDictionary class.

Public Sub Add(ByVal key As Object, ByVal value As Object) Implements IDictionary.Add

   ' Add the new key/value pair even if this key already exists in the dictionary.
   If ItemsInUse = items.Length Then
      Throw New InvalidOperationException("The dictionary cannot hold any more items.")
   End If
   items(ItemsInUse) = New DictionaryEntry(key, value)
   ItemsInUse = ItemsInUse + 1
End Sub
public void Add(object key, object value)
{
   // Add the new key/value pair even if this key already exists in the dictionary.
   if (ItemsInUse == items.Length)
      throw new InvalidOperationException("The dictionary cannot hold any more items.");
   items[ItemsInUse++] = new DictionaryEntry(key, value);
}

Version Information

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Platforms

Windows Phone

See Also

Reference

IDictionary Interface

System.Collections Namespace

Item