OrderedDictionary.Contains(Object) 方法

定义

命名空间:

System.Collections.Specialized

程序集:

System.Collections.Specialized.dll

Source:

OrderedDictionary.cs

确定 OrderedDictionary 集合是否包含特定的键。

public:
 virtual bool Contains(System::Object ^ key);

public bool Contains (object key);

abstract member Contains : obj -> bool
override this.Contains : obj -> bool

Public Function Contains (key As Object) As Boolean

参数

key

Object

要在 OrderedDictionary 集合中定位的键。

返回

Boolean

如果 OrderedDictionary 集合包含具有指定键的元素，则为 true；否则为 false。

实现

Contains(Object)

示例

下面的代码示例演示了对集合的 OrderedDictionary 修改。 在此示例中， Contains 方法用于确定某个条目是否存在，然后再尝试删除它。 此代码是可在 中查看的较大代码示例的一 OrderedDictionary部分。

// Modifying the OrderedDictionary
if (!myOrderedDictionary->IsReadOnly)
{
    // Insert a new key to the beginning of the OrderedDictionary
    myOrderedDictionary->Insert(0, "insertedKey1", "insertedValue1");

    // Modify the value of the entry with the key "testKey2"
    myOrderedDictionary["testKey2"] = "modifiedValue";

    // Remove the last entry from the OrderedDictionary: "testKey3"
    myOrderedDictionary->RemoveAt(myOrderedDictionary->Count - 1);

    // Remove the "keyToDelete" entry, if it exists
    if (myOrderedDictionary->Contains("keyToDelete"))
    {
        myOrderedDictionary->Remove("keyToDelete");
    }
}

// Modifying the OrderedDictionary
if (!myOrderedDictionary.IsReadOnly)
{
    // Insert a new key to the beginning of the OrderedDictionary
    myOrderedDictionary.Insert(0, "insertedKey1", "insertedValue1");

    // Modify the value of the entry with the key "testKey2"
    myOrderedDictionary["testKey2"] = "modifiedValue";

    // Remove the last entry from the OrderedDictionary: "testKey3"
    myOrderedDictionary.RemoveAt(myOrderedDictionary.Count - 1);

    // Remove the "keyToDelete" entry, if it exists
    if (myOrderedDictionary.Contains("keyToDelete"))
    {
        myOrderedDictionary.Remove("keyToDelete");
    }
}

' Modifying the OrderedDictionary
If Not myOrderedDictionary.IsReadOnly Then

    ' Insert a new key to the beginning of the OrderedDictionary
    myOrderedDictionary.Insert(0, "insertedKey1", "insertedValue1")

    ' Modify the value of the entry with the key "testKey2"
    myOrderedDictionary("testKey2") = "modifiedValue"

    ' Remove the last entry from the OrderedDictionary: "testKey3"
    myOrderedDictionary.RemoveAt(myOrderedDictionary.Count - 1)

    ' Remove the "keyToDelete" entry, if it exists
    If (myOrderedDictionary.Contains("keyToDelete")) Then
        myOrderedDictionary.Remove("keyToDelete")
    End If
End If

注解

Item[]如果键不存在或键null为 ，则使用 属性可以返回 null 值。 Contains使用 方法可确定集合中OrderedDictionary是否存在特定键。

从 .NET Framework 2.0 开始，此方法使用 集合的对象 Equals 和 CompareTo 方法item来确定是否存在item。 在早期版本的 .NET Framework中，此确定是通过对集合中的 对象使用 Equals 参数的 item 和 CompareTo 方法做出的。