Parameters

key

The key of the element to add to the dictionary.

value

The value of the element to add to the dictionary.

Exceptions

Type	Reason
ArgumentException	An element with the same key already exists in the dictionary.
ArgumentNullException	key is null.

Remarks

You can also use the Dictionary<TKey, TValue>.Item(TKey) property to add new elements by setting the value of a key that does not exist in the dictionary. However, if the specified key already exists in the dictionary, setting the Dictionary<TKey, TValue>.Item(TKey) property overwrites the old value. In contrast, the Dictionary<TKey, TValue>.Add(TKey,TValue) method does not modify existing elements.

If Dictionary<TKey, TValue>.Count already equals the capacity, the capacity of the dictionary is increased.

A key cannot be ., but a value can be, if the value type TValue is a reference type.

Requirements

Namespace: System.Collections.Generic
Assembly: mscorlib (in mscorlib.dll)
Assembly Versions: 2.0.0.0
Since: .NET 2.0