Dictionary<TKey,TValue>.Remove Method

Definition

Namespace:

System.Collections.Generic

Assembly:

System.Collections.dll

Overloads

Remove(TKey)	Removes the value with the specified key from the Dictionary<TKey,TValue>.
Remove(TKey, TValue)	Removes the value with the specified key from the Dictionary<TKey,TValue>, and copies the element to the value parameter.

Remove(TKey)

Source:

Dictionary.cs

Removes the value with the specified key from the Dictionary<TKey,TValue>.

public:
 virtual bool Remove(TKey key);

public bool Remove (TKey key);

abstract member Remove : 'Key -> bool
override this.Remove : 'Key -> bool

Public Function Remove (key As TKey) As Boolean

Parameters

key

TKey

The key of the element to remove.

Returns

Boolean

true if the element is successfully found and removed; otherwise, false. This method returns false if key is not found in the Dictionary<TKey,TValue>.

Implements

Remove(TKey)

Exceptions

ArgumentNullException

key is null.

Examples

The following code example shows how to remove a key/value pair from a dictionary using the Remove method.

This code example is part of a larger example provided for the Dictionary<TKey,TValue> class (openWith is the name of the Dictionary used in this example).

// Use the Remove method to remove a key/value pair.
Console::WriteLine("\nRemove(\"doc\")");
openWith->Remove("doc");

if (!openWith->ContainsKey("doc"))
{
    Console::WriteLine("Key \"doc\" is not found.");
}

// Use the Remove method to remove a key/value pair.
Console.WriteLine("\nRemove(\"doc\")");
openWith.Remove("doc");

if (!openWith.ContainsKey("doc"))
{
    Console.WriteLine("Key \"doc\" is not found.");
}

// Use the Remove method to remove a key/value pair.
printfn "\nRemove(\"doc\")"
openWith.Remove "doc" |> ignore

if openWith.ContainsKey "doc" |> not then
    printfn "Key \"doc\" is not found."

' Use the Remove method to remove a key/value pair.
Console.WriteLine(vbLf + "Remove(""doc"")")
openWith.Remove("doc")

If Not openWith.ContainsKey("doc") Then
    Console.WriteLine("Key ""doc"" is not found.")
End If

Remarks

If the Dictionary<TKey,TValue> does not contain an element with the specified key, the Dictionary<TKey,TValue> remains unchanged. No exception is thrown.

This method approaches an O(1) operation.

.NET Core 3.0+ only: this mutating method may be safely called without invalidating active enumerators on the Dictionary<TKey,TValue> instance. This does not imply thread safety.

See also

• Add(TKey, TValue)
• Remove(TKey)

Remove(TKey, TValue)

Source:

Dictionary.cs

Removes the value with the specified key from the Dictionary<TKey,TValue>, and copies the element to the value parameter.

public:
 bool Remove(TKey key, [Runtime::InteropServices::Out] TValue % value);

public bool Remove (TKey key, out TValue value);

member this.Remove : 'Key * 'Value -> bool

Public Function Remove (key As TKey, ByRef value As TValue) As Boolean

Parameters

key

TKey

The key of the element to remove.

value

TValue

The removed element.

Returns

Boolean

true if the element is successfully found and removed; otherwise, false.

Exceptions

ArgumentNullException

key is null.