Dictionary<TKey,TValue>.Add() Method is used to add a specified key and value to the dictionary.
public void Add (TKey key, TValue value);
key: It is the key of the element to add.
value: It is the value of the element to add. The value can be null for reference types.
- ArgumentNullException : If the key is null.
- ArgumentException : If an element with the same key already exists in the Dictionary.
Below are the programs to illustrate the use of Dictionary<TKey,TValue>.Add() Method:
Total key/value pairs in myDict are : 6 The key/value pairs in myDict are : 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
An element with Key = "Russia" already exists.
- A key cannot be null, but a value can be if TValue is a reference type.
- If Count is less than the capacity, this method approaches an O(1) operation.
- If the capacity must be increased to accommodate the new element, this method becomes an O(n) operation, where n is Count.