HashSet<T>.IsSubsetOf(IEnumerable<T>) 方法

定义

命名空间:

System.Collections.Generic

程序集:

System.Collections.dll

Source:

HashSet.cs

确定 HashSet<T> 对象是否为指定集合的子集。

public:
 virtual bool IsSubsetOf(System::Collections::Generic::IEnumerable<T> ^ other);

public bool IsSubsetOf (System.Collections.Generic.IEnumerable<T> other);

abstract member IsSubsetOf : seq<'T> -> bool
override this.IsSubsetOf : seq<'T> -> bool

Public Function IsSubsetOf (other As IEnumerable(Of T)) As Boolean

参数

other

IEnumerable<T>

要与当前的 HashSet<T> 对象进行比较的集合。

返回

Boolean

如果 HashSet<T> 对象是 other 的子集，则为 true；否则为 false。

实现

IsSubsetOf(IEnumerable<T>) IsSubsetOf(IEnumerable<T>)

例外

ArgumentNullException

other 为 null。

示例

以下示例创建两个不同的 HashSet<T> 对象，并将它们相互比较。 在此示例中， lowNumbers 是 的子集和适当的子集 allNumbers ，直到 allNumbers 使用 IntersectWith 方法进行修改，以仅包含两个集中存在的值。 一旦 allNumbers 和 相同， lowNumbers 仍然是 的子集，allNumbers但不再是lowNumbers适当的子集。

HashSet<int> lowNumbers = new HashSet<int>();
HashSet<int> allNumbers = new HashSet<int>();

for (int i = 1; i < 5; i++)
{
    lowNumbers.Add(i);
}

for (int i = 0; i < 10; i++)
{
    allNumbers.Add(i);
}

Console.Write("lowNumbers contains {0} elements: ", lowNumbers.Count);
DisplaySet(lowNumbers);

Console.Write("allNumbers contains {0} elements: ", allNumbers.Count);
DisplaySet(allNumbers);

Console.WriteLine("lowNumbers overlaps allNumbers: {0}",
    lowNumbers.Overlaps(allNumbers));

Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}",
    allNumbers.SetEquals(lowNumbers));

// Show the results of sub/superset testing
Console.WriteLine("lowNumbers is a subset of allNumbers: {0}",
    lowNumbers.IsSubsetOf(allNumbers));
Console.WriteLine("allNumbers is a superset of lowNumbers: {0}",
    allNumbers.IsSupersetOf(lowNumbers));
Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}",
    lowNumbers.IsProperSubsetOf(allNumbers));
Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}",
    allNumbers.IsProperSupersetOf(lowNumbers));

// Modify allNumbers to remove numbers that are not in lowNumbers.
allNumbers.IntersectWith(lowNumbers);
Console.Write("allNumbers contains {0} elements: ", allNumbers.Count);
DisplaySet(allNumbers);

Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}",
    allNumbers.SetEquals(lowNumbers));

// Show the results of sub/superset testing with the modified set.
Console.WriteLine("lowNumbers is a subset of allNumbers: {0}",
    lowNumbers.IsSubsetOf(allNumbers));
Console.WriteLine("allNumbers is a superset of lowNumbers: {0}",
    allNumbers.IsSupersetOf(lowNumbers));
Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}",
    lowNumbers.IsProperSubsetOf(allNumbers));
Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}",
    allNumbers.IsProperSupersetOf(lowNumbers));

void DisplaySet(HashSet<int> set)
{
    Console.Write("{");
    foreach (int i in set)
    {
        Console.Write(" {0}", i);
    }
    Console.WriteLine(" }");
}

/* This code example produces output similar to the following:
* lowNumbers contains 4 elements: { 1 2 3 4 }
* allNumbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
* lowNumbers overlaps allNumbers: True
* allNumbers and lowNumbers are equal sets: False
* lowNumbers is a subset of allNumbers: True
* allNumbers is a superset of lowNumbers: True
* lowNumbers is a proper subset of allNumbers: True
* allNumbers is a proper superset of lowNumbers: True
* allNumbers contains 4 elements: { 1 2 3 4 }
* allNumbers and lowNumbers are equal sets: True
* lowNumbers is a subset of allNumbers: True
* allNumbers is a superset of lowNumbers: True
* lowNumbers is a proper subset of allNumbers: False
* allNumbers is a proper superset of lowNumbers: False
*/

Shared Sub Main()

    Dim lowNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()
    Dim allNumbers As HashSet(Of Integer) = New HashSet(Of Integer)()

    For i As Integer = 1 To 4
        lowNumbers.Add(i)
    Next i

    For i As Integer = 0 To 9
        allNumbers.Add(i)
    Next i


    Console.Write("lowNumbers contains {0} elements: ", lowNumbers.Count)
    DisplaySet(lowNumbers)

    Console.Write("allNumbers contains {0} elements: ", allNumbers.Count)
    DisplaySet(allNumbers)

    Console.WriteLine("lowNumbers overlaps allNumbers: {0}", _
        lowNumbers.Overlaps(allNumbers))

    Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}", _
        allNumbers.SetEquals(lowNumbers))

    ' Show the results of sub/superset testing
    Console.WriteLine("lowNumbers is a subset of allNumbers: {0}", _
        lowNumbers.IsSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a superset of lowNumbers: {0}", _
        allNumbers.IsSupersetOf(lowNumbers))
    Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}", _
        lowNumbers.IsProperSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}", _
        allNumbers.IsProperSupersetOf(lowNumbers))

    ' Modify allNumbers to remove numbers that are not in lowNumbers.
    allNumbers.IntersectWith(lowNumbers)
    Console.Write("allNumbers contains {0} elements: ", allNumbers.Count)
    DisplaySet(allNumbers)

    Console.WriteLine("allNumbers and lowNumbers are equal sets: {0}", _
        allNumbers.SetEquals(lowNumbers))

    ' Show the results of sub/superset testing with the modified set.
    Console.WriteLine("lowNumbers is a subset of allNumbers: {0}", _
        lowNumbers.IsSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a superset of lowNumbers: {0}", _
        allNumbers.IsSupersetOf(lowNumbers))
    Console.WriteLine("lowNumbers is a proper subset of allNumbers: {0}", _
        lowNumbers.IsProperSubsetOf(allNumbers))
    Console.WriteLine("allNumbers is a proper superset of lowNumbers: {0}", _
        allNumbers.IsProperSupersetOf(lowNumbers))
End Sub
' This code example produces output similar to the following:
' lowNumbers contains 4 elements: { 1 2 3 4 }
' allNumbers contains 10 elements: { 0 1 2 3 4 5 6 7 8 9 }
' lowNumbers overlaps allNumbers: True
' allNumbers and lowNumbers are equal sets: False
' lowNumbers is a subset of allNumbers: True
' allNumbers is a superset of lowNumbers: True
' lowNumbers is a proper subset of allNumbers: True
' allNumbers is a proper superset of lowNumbers: True
' allNumbers contains 4 elements: { 1 2 3 4 }
' allNumbers and lowNumbers are equal sets: True
' lowNumbers is a subset of allNumbers: True
' allNumbers is a superset of lowNumbers: True
' lowNumbers is a proper subset of allNumbers: False
' allNumbers is a proper superset of lowNumbers: False

注解

空集是任何其他集合的子集，包括空集;因此，如果由当前HashSet<T>对象表示的集合为空，则此方法返回 true ，即使 参数other为空集也是如此。

如果 Count 大于 中的other元素数，则此方法始终返回 false 。

如果 表示的 other 集合是一个 HashSet<T> 与当前 HashSet<T> 对象具有相同相等比较器的集合，则此方法是 O (n) 操作。 否则，此方法为 O (n + m) 操作，其中 n 是 Count 和 m 中的 other元素数。