# HashSet(Of T) Class

**.NET Framework 4.6 and 4.5**

Represents a set of values.

To browse the .NET Framework source code for this type, see the Reference Source.

**Namespace:**System.Collections.Generic

**Assemblies:**System.Core (in System.Core.dll)

System.Collections (in System.Collections.dll)

'Declaration <SerializableAttribute> _ <DebuggerDisplayAttribute("Count = {Count}")> _ <HostProtectionAttribute(SecurityAction.LinkDemand, MayLeakOnAbort := True)> _ Public Class HashSet(Of T) _ Implements ICollection(Of T), IEnumerable(Of T), _ IEnumerable, ISerializable, IDeserializationCallback, ISet(Of T), IReadOnlyCollection(Of T)

#### Type Parameters

- T
The type of elements in the hash set.

The HashSet(Of T) type exposes the following members.

Name | Description | |
---|---|---|

HashSet(Of T) | Initializes a new instance of the HashSet(Of T) class that is empty and uses the default equality comparer for the set type. | |

HashSet(Of T)(IEnumerable(Of T)) | Initializes a new instance of the HashSet(Of T) class that uses the default equality comparer for the set type, contains elements copied from the specified collection, and has sufficient capacity to accommodate the number of elements copied. | |

HashSet(Of T)(IEqualityComparer(Of T)) | Initializes a new instance of the HashSet(Of T) class that is empty and uses the specified equality comparer for the set type. | |

HashSet(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Initializes a new instance of the HashSet(Of T) class that uses the specified equality comparer for the set type, contains elements copied from the specified collection, and has sufficient capacity to accommodate the number of elements copied. | |

HashSet(Of T)(SerializationInfo, StreamingContext) | Initializes a new instance of the HashSet(Of T) class with serialized data. |

Name | Description | |
---|---|---|

Comparer | Gets the IEqualityComparer(Of T) object that is used to determine equality for the values in the set. | |

Count | Gets the number of elements that are contained in a set. |

Name | Description | |
---|---|---|

Add | Adds the specified element to a set. | |

Clear | Removes all elements from a HashSet(Of T) object. | |

Contains | Determines whether a HashSet(Of T) object contains the specified element. | |

CopyTo(T()) | Copies the elements of a HashSet(Of T) object to an array. | |

CopyTo(T(), Int32) | Copies the elements of a HashSet(Of T) object to an array, starting at the specified array index. | |

CopyTo(T(), Int32, Int32) | Copies the specified number of elements of a HashSet(Of T) object to an array, starting at the specified array index. | |

CreateSetComparer | Returns an IEqualityComparer object that can be used for equality testing of a HashSet(Of T) object. | |

Equals(Object) | Determines whether the specified object is equal to the current object. (Inherited from Object.) | |

ExceptWith | Removes all elements in the specified collection from the current HashSet(Of T) object. | |

Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) | |

GetEnumerator | Returns an enumerator that iterates through a HashSet(Of T) object. | |

GetHashCode | Serves as the default hash function. (Inherited from Object.) | |

GetObjectData | Implements the System.Runtime.Serialization.ISerializable interface and returns the data needed to serialize a HashSet(Of T) object. | |

GetType | Gets the Type of the current instance. (Inherited from Object.) | |

IntersectWith | Modifies the current HashSet(Of T) object to contain only elements that are present in that object and in the specified collection. | |

IsProperSubsetOf | Determines whether a HashSet(Of T) object is a proper subset of the specified collection. | |

IsProperSupersetOf | Determines whether a HashSet(Of T) object is a proper superset of the specified collection. | |

IsSubsetOf | Determines whether a HashSet(Of T) object is a subset of the specified collection. | |

IsSupersetOf | Determines whether a HashSet(Of T) object is a superset of the specified collection. | |

MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) | |

OnDeserialization | Implements the System.Runtime.Serialization.ISerializable interface and raises the deserialization event when the deserialization is complete. | |

Overlaps | Determines whether the current HashSet(Of T) object and a specified collection share common elements. | |

Remove | Removes the specified element from a HashSet(Of T) object. | |

RemoveWhere | Removes all elements that match the conditions defined by the specified predicate from a HashSet(Of T) collection. | |

SetEquals | Determines whether a HashSet(Of T) object and the specified collection contain the same elements. | |

SymmetricExceptWith | Modifies the current HashSet(Of T) object to contain only elements that are present either in that object or in the specified collection, but not both. | |

ToString | Returns a string that represents the current object. (Inherited from Object.) | |

TrimExcess | Sets the capacity of a HashSet(Of T) object to the actual number of elements it contains, rounded up to a nearby, implementation-specific value. | |

UnionWith | Modifies the current HashSet(Of T) object to contain all elements that are present in itself, the specified collection, or both. |

Name | Description | |
---|---|---|

Aggregate(Of T)(Func(Of T, T, T)) | Overloaded. Applies an accumulator function over a sequence. (Defined by Enumerable.) | |

Aggregate(Of T)(Func(Of T, T, T)) | Overloaded. (Defined by Enumerable.) | |

Aggregate(Of T, TAccumulate)(TAccumulate, Func(Of TAccumulate, T, TAccumulate)) | Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value. (Defined by Enumerable.) | |

Aggregate(Of T, TAccumulate)(TAccumulate, Func(Of TAccumulate, T, TAccumulate)) | Overloaded. (Defined by Enumerable.) | |

Aggregate(Of T, TAccumulate, TResult)(TAccumulate, Func(Of TAccumulate, T, TAccumulate), Func(Of TAccumulate, TResult)) | Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value. (Defined by Enumerable.) | |

Aggregate(Of T, TAccumulate, TResult)(TAccumulate, Func(Of TAccumulate, T, TAccumulate), Func(Of TAccumulate, TResult)) | Overloaded. (Defined by Enumerable.) | |

All(Of T)(Func(Of T, Boolean)) | Overloaded. Determines whether all elements of a sequence satisfy a condition. (Defined by Enumerable.) | |

All(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

Any(Of T) | Overloaded. Determines whether a sequence contains any elements. (Defined by Enumerable.) | |

Any(Of T) | Overloaded. (Defined by Enumerable.) | |

Any(Of T)(Func(Of T, Boolean)) | Overloaded. Determines whether any element of a sequence satisfies a condition. (Defined by Enumerable.) | |

Any(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

AsEnumerable(Of T) | Overloaded. Returns the input typed as IEnumerable(Of T). (Defined by Enumerable.) | |

AsEnumerable(Of T) | Overloaded. (Defined by Enumerable.) | |

AsParallel | Overloaded. Enables parallelization of a query. (Defined by ParallelEnumerable.) | |

AsParallel | Overloaded. (Defined by ParallelEnumerable.) | |

AsParallel(Of T) | Overloaded. Enables parallelization of a query. (Defined by ParallelEnumerable.) | |

AsParallel(Of T) | Overloaded. (Defined by ParallelEnumerable.) | |

AsQueryable | Overloaded. Converts an IEnumerable to an IQueryable. (Defined by Queryable.) | |

AsQueryable | Overloaded. (Defined by Queryable.) | |

AsQueryable(Of T) | Overloaded. Converts a generic IEnumerable(Of T) to a generic IQueryable(Of T). (Defined by Queryable.) | |

AsQueryable(Of T) | Overloaded. (Defined by Queryable.) | |

Average(Of T)(Func(Of T, Decimal)) | Overloaded. Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. Computes the average of a sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Decimal)) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Double)) | Overloaded. Computes the average of a sequence of Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. Computes the average of a sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Double)) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Int32)) | Overloaded. Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Int64)) | Overloaded. Computes the average of a sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Single)) | Overloaded. Computes the average of a sequence of Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. Computes the average of a sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Int32)) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Int64)) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. (Defined by Enumerable.) | |

Average(Of T)(Func(Of T, Single)) | Overloaded. (Defined by Enumerable.) | |

Cast(Of TResult) | Overloaded. Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.) | |

Cast(Of TResult) | Overloaded. (Defined by Enumerable.) | |

Concat(Of T)(IEnumerable(Of T)) | Overloaded. Concatenates two sequences. (Defined by Enumerable.) | |

Concat(Of T)(IEnumerable(Of T)) | Overloaded. (Defined by Enumerable.) | |

Contains(Of T)(T) | Overloaded. Determines whether a sequence contains a specified element by using the default equality comparer. (Defined by Enumerable.) | |

Contains(Of T)(T) | Overloaded. (Defined by Enumerable.) | |

Contains(Of T)(T, IEqualityComparer(Of T)) | Overloaded. Determines whether a sequence contains a specified element by using a specified IEqualityComparer(Of T). (Defined by Enumerable.) | |

Contains(Of T)(T, IEqualityComparer(Of T)) | Overloaded. (Defined by Enumerable.) | |

Count(Of T) | Overloaded. Returns the number of elements in a sequence. (Defined by Enumerable.) | |

Count(Of T) | Overloaded. (Defined by Enumerable.) | |

Count(Of T)(Func(Of T, Boolean)) | Overloaded. Returns a number that represents how many elements in the specified sequence satisfy a condition. (Defined by Enumerable.) | |

Count(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

DefaultIfEmpty(Of T) | Overloaded. Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty. (Defined by Enumerable.) | |

DefaultIfEmpty(Of T) | Overloaded. (Defined by Enumerable.) | |

DefaultIfEmpty(Of T)(T) | Overloaded. Returns the elements of the specified sequence or the specified value in a singleton collection if the sequence is empty. (Defined by Enumerable.) | |

DefaultIfEmpty(Of T)(T) | Overloaded. (Defined by Enumerable.) | |

Distinct(Of T) | Overloaded. Returns distinct elements from a sequence by using the default equality comparer to compare values. (Defined by Enumerable.) | |

Distinct(Of T) | Overloaded. (Defined by Enumerable.) | |

Distinct(Of T)(IEqualityComparer(Of T)) | Overloaded. Returns distinct elements from a sequence by using a specified IEqualityComparer(Of T) to compare values. (Defined by Enumerable.) | |

Distinct(Of T)(IEqualityComparer(Of T)) | Overloaded. (Defined by Enumerable.) | |

ElementAt(Of T)(Int32) | Overloaded. Returns the element at a specified index in a sequence. (Defined by Enumerable.) | |

ElementAt(Of T)(Int32) | Overloaded. (Defined by Enumerable.) | |

ElementAtOrDefault(Of T)(Int32) | Overloaded. Returns the element at a specified index in a sequence or a default value if the index is out of range. (Defined by Enumerable.) | |

ElementAtOrDefault(Of T)(Int32) | Overloaded. (Defined by Enumerable.) | |

Except(Of T)(IEnumerable(Of T)) | Overloaded. Produces the set difference of two sequences by using the default equality comparer to compare values. (Defined by Enumerable.) | |

Except(Of T)(IEnumerable(Of T)) | Overloaded. (Defined by Enumerable.) | |

Except(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. Produces the set difference of two sequences by using the specified IEqualityComparer(Of T) to compare values. (Defined by Enumerable.) | |

Except(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. (Defined by Enumerable.) | |

First(Of T) | Overloaded. Returns the first element of a sequence. (Defined by Enumerable.) | |

First(Of T) | Overloaded. (Defined by Enumerable.) | |

First(Of T)(Func(Of T, Boolean)) | Overloaded. Returns the first element in a sequence that satisfies a specified condition. (Defined by Enumerable.) | |

First(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

FirstOrDefault(Of T) | Overloaded. Returns the first element of a sequence, or a default value if the sequence contains no elements. (Defined by Enumerable.) | |

FirstOrDefault(Of T) | Overloaded. (Defined by Enumerable.) | |

FirstOrDefault(Of T)(Func(Of T, Boolean)) | Overloaded. Returns the first element of the sequence that satisfies a condition or a default value if no such element is found. (Defined by Enumerable.) | |

FirstOrDefault(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey)(Func(Of T, TKey)) | Overloaded. Groups the elements of a sequence according to a specified key selector function. (Defined by Enumerable.) | |

GroupBy(Of T, TKey)(Func(Of T, TKey)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey)(Func(Of T, TKey), IEqualityComparer(Of TKey)) | Overloaded. Groups the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer. (Defined by Enumerable.) | |

GroupBy(Of T, TKey)(Func(Of T, TKey), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement)) | Overloaded. Groups the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TResult)(Func(Of T, TKey), Func(Of TKey, IEnumerable(Of T), TResult)) | Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TResult)(Func(Of T, TKey), Func(Of TKey, IEnumerable(Of T), TResult)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement), IEqualityComparer(Of TKey)) | Overloaded. Groups the elements of a sequence according to a key selector function. The keys are compared by using a comparer and each group's elements are projected by using a specified function. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TResult)(Func(Of T, TKey), Func(Of TKey, IEnumerable(Of T), TResult), IEqualityComparer(Of TKey)) | Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TResult)(Func(Of T, TKey), Func(Of TKey, IEnumerable(Of T), TResult), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement, TResult)(Func(Of T, TKey), Func(Of T, TElement), Func(Of TKey, IEnumerable(Of TElement), TResult)) | Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The elements of each group are projected by using a specified function. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement, TResult)(Func(Of T, TKey), Func(Of T, TElement), Func(Of TKey, IEnumerable(Of TElement), TResult)) | Overloaded. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement, TResult)(Func(Of T, TKey), Func(Of T, TElement), Func(Of TKey, IEnumerable(Of TElement), TResult), IEqualityComparer(Of TKey)) | Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. Key values are compared by using a specified comparer, and the elements of each group are projected by using a specified function. (Defined by Enumerable.) | |

GroupBy(Of T, TKey, TElement, TResult)(Func(Of T, TKey), Func(Of T, TElement), Func(Of TKey, IEnumerable(Of TElement), TResult), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

GroupJoin(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, IEnumerable(Of TInner), TResult)) | Overloaded. Correlates the elements of two sequences based on equality of keys and groups the results. The default equality comparer is used to compare keys. (Defined by Enumerable.) | |

GroupJoin(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, IEnumerable(Of TInner), TResult)) | Overloaded. (Defined by Enumerable.) | |

GroupJoin(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, IEnumerable(Of TInner), TResult), IEqualityComparer(Of TKey)) | Overloaded. Correlates the elements of two sequences based on key equality and groups the results. A specified IEqualityComparer(Of T) is used to compare keys. (Defined by Enumerable.) | |

GroupJoin(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, IEnumerable(Of TInner), TResult), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

Intersect(Of T)(IEnumerable(Of T)) | Overloaded. Produces the set intersection of two sequences by using the default equality comparer to compare values. (Defined by Enumerable.) | |

Intersect(Of T)(IEnumerable(Of T)) | Overloaded. (Defined by Enumerable.) | |

Intersect(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. Produces the set intersection of two sequences by using the specified IEqualityComparer(Of T) to compare values. (Defined by Enumerable.) | |

Intersect(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. (Defined by Enumerable.) | |

Join(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, TInner, TResult)) | Overloaded. Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys. (Defined by Enumerable.) | |

Join(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, TInner, TResult)) | Overloaded. (Defined by Enumerable.) | |

Join(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, TInner, TResult), IEqualityComparer(Of TKey)) | Overloaded. Correlates the elements of two sequences based on matching keys. A specified IEqualityComparer(Of T) is used to compare keys. (Defined by Enumerable.) | |

Join(Of T, TInner, TKey, TResult)(IEnumerable(Of TInner), Func(Of T, TKey), Func(Of TInner, TKey), Func(Of T, TInner, TResult), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

Last(Of T) | Overloaded. Returns the last element of a sequence. (Defined by Enumerable.) | |

Last(Of T) | Overloaded. (Defined by Enumerable.) | |

Last(Of T)(Func(Of T, Boolean)) | Overloaded. Returns the last element of a sequence that satisfies a specified condition. (Defined by Enumerable.) | |

Last(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

LastOrDefault(Of T) | Overloaded. Returns the last element of a sequence, or a default value if the sequence contains no elements. (Defined by Enumerable.) | |

LastOrDefault(Of T) | Overloaded. (Defined by Enumerable.) | |

LastOrDefault(Of T)(Func(Of T, Boolean)) | Overloaded. Returns the last element of a sequence that satisfies a condition or a default value if no such element is found. (Defined by Enumerable.) | |

LastOrDefault(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

LongCount(Of T) | Overloaded. Returns an Int64 that represents the total number of elements in a sequence. (Defined by Enumerable.) | |

LongCount(Of T) | Overloaded. (Defined by Enumerable.) | |

LongCount(Of T)(Func(Of T, Boolean)) | Overloaded. Returns an Int64 that represents how many elements in a sequence satisfy a condition. (Defined by Enumerable.) | |

LongCount(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

Max(Of T) | Overloaded. Returns the maximum value in a generic sequence. (Defined by Enumerable.) | |

Max(Of T) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Decimal)) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Decimal value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Decimal value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Decimal)) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Double)) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Double value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Double value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Double)) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Int32)) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int32 value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int32 value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Int64)) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int64 value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int64 value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Single)) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Single value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Single value. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Int32)) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Int64)) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. (Defined by Enumerable.) | |

Max(Of T)(Func(Of T, Single)) | Overloaded. (Defined by Enumerable.) | |

Max(Of T, TResult)(Func(Of T, TResult)) | Overloaded. Invokes a transform function on each element of a generic sequence and returns the maximum resulting value. (Defined by Enumerable.) | |

Max(Of T, TResult)(Func(Of T, TResult)) | Overloaded. (Defined by Enumerable.) | |

Min(Of T) | Overloaded. Returns the minimum value in a generic sequence. (Defined by Enumerable.) | |

Min(Of T) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Decimal)) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Decimal value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Decimal value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Decimal)) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Double)) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Double value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Double value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Double)) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Int32)) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int32 value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int32 value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Int64)) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int64 value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int64 value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Single)) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Single value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Single value. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Int32)) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Int64)) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. (Defined by Enumerable.) | |

Min(Of T)(Func(Of T, Single)) | Overloaded. (Defined by Enumerable.) | |

Min(Of T, TResult)(Func(Of T, TResult)) | Overloaded. Invokes a transform function on each element of a generic sequence and returns the minimum resulting value. (Defined by Enumerable.) | |

Min(Of T, TResult)(Func(Of T, TResult)) | Overloaded. (Defined by Enumerable.) | |

OfType(Of TResult) | Overloaded. Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.) | |

OfType(Of TResult) | Overloaded. (Defined by Enumerable.) | |

OrderBy(Of T, TKey)(Func(Of T, TKey)) | Overloaded. Sorts the elements of a sequence in ascending order according to a key. (Defined by Enumerable.) | |

OrderBy(Of T, TKey)(Func(Of T, TKey)) | Overloaded. (Defined by Enumerable.) | |

OrderBy(Of T, TKey)(Func(Of T, TKey), IComparer(Of TKey)) | Overloaded. Sorts the elements of a sequence in ascending order by using a specified comparer. (Defined by Enumerable.) | |

OrderBy(Of T, TKey)(Func(Of T, TKey), IComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

OrderByDescending(Of T, TKey)(Func(Of T, TKey)) | Overloaded. Sorts the elements of a sequence in descending order according to a key. (Defined by Enumerable.) | |

OrderByDescending(Of T, TKey)(Func(Of T, TKey)) | Overloaded. (Defined by Enumerable.) | |

OrderByDescending(Of T, TKey)(Func(Of T, TKey), IComparer(Of TKey)) | Overloaded. Sorts the elements of a sequence in descending order by using a specified comparer. (Defined by Enumerable.) | |

OrderByDescending(Of T, TKey)(Func(Of T, TKey), IComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

Reverse(Of T) | Overloaded. Inverts the order of the elements in a sequence. (Defined by Enumerable.) | |

Reverse(Of T) | Overloaded. (Defined by Enumerable.) | |

Select(Of T, TResult)(Func(Of T, TResult)) | Overloaded. Projects each element of a sequence into a new form. (Defined by Enumerable.) | |

Select(Of T, TResult)(Func(Of T, Int32, TResult)) | Overloaded. Projects each element of a sequence into a new form by incorporating the element's index. (Defined by Enumerable.) | |

Select(Of T, TResult)(Func(Of T, TResult)) | Overloaded. (Defined by Enumerable.) | |

Select(Of T, TResult)(Func(Of T, Int32, TResult)) | Overloaded. (Defined by Enumerable.) | |

SelectMany(Of T, TResult)(Func(Of T, IEnumerable(Of TResult))) | Overloaded. Projects each element of a sequence to an IEnumerable(Of T) and flattens the resulting sequences into one sequence. (Defined by Enumerable.) | |

SelectMany(Of T, TResult)(Func(Of T, Int32, IEnumerable(Of TResult))) | Overloaded. Projects each element of a sequence to an IEnumerable(Of T), and flattens the resulting sequences into one sequence. The index of each source element is used in the projected form of that element. (Defined by Enumerable.) | |

SelectMany(Of T, TResult)(Func(Of T, IEnumerable(Of TResult))) | Overloaded. (Defined by Enumerable.) | |

SelectMany(Of T, TResult)(Func(Of T, Int32, IEnumerable(Of TResult))) | Overloaded. (Defined by Enumerable.) | |

SelectMany(Of T, TCollection, TResult)(Func(Of T, Int32, IEnumerable(Of TCollection)), Func(Of T, TCollection, TResult)) | Overloaded. Projects each element of a sequence to an IEnumerable(Of T), flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element. (Defined by Enumerable.) | |

SelectMany(Of T, TCollection, TResult)(Func(Of T, IEnumerable(Of TCollection)), Func(Of T, TCollection, TResult)) | Overloaded. Projects each element of a sequence to an IEnumerable(Of T), flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. (Defined by Enumerable.) | |

SelectMany(Of T, TCollection, TResult)(Func(Of T, IEnumerable(Of TCollection)), Func(Of T, TCollection, TResult)) | Overloaded. (Defined by Enumerable.) | |

SelectMany(Of T, TCollection, TResult)(Func(Of T, Int32, IEnumerable(Of TCollection)), Func(Of T, TCollection, TResult)) | Overloaded. (Defined by Enumerable.) | |

SequenceEqual(Of T)(IEnumerable(Of T)) | Overloaded. Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type. (Defined by Enumerable.) | |

SequenceEqual(Of T)(IEnumerable(Of T)) | Overloaded. (Defined by Enumerable.) | |

SequenceEqual(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer(Of T). (Defined by Enumerable.) | |

SequenceEqual(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. (Defined by Enumerable.) | |

Single(Of T) | Overloaded. Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence. (Defined by Enumerable.) | |

Single(Of T) | Overloaded. (Defined by Enumerable.) | |

Single(Of T)(Func(Of T, Boolean)) | Overloaded. Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists. (Defined by Enumerable.) | |

Single(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

SingleOrDefault(Of T) | Overloaded. Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence. (Defined by Enumerable.) | |

SingleOrDefault(Of T) | Overloaded. (Defined by Enumerable.) | |

SingleOrDefault(Of T)(Func(Of T, Boolean)) | Overloaded. Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition. (Defined by Enumerable.) | |

SingleOrDefault(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

Skip(Of T)(Int32) | Overloaded. Bypasses a specified number of elements in a sequence and then returns the remaining elements. (Defined by Enumerable.) | |

Skip(Of T)(Int32) | Overloaded. (Defined by Enumerable.) | |

SkipWhile(Of T)(Func(Of T, Boolean)) | Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. (Defined by Enumerable.) | |

SkipWhile(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

SkipWhile(Of T)(Func(Of T, Int32, Boolean)) | Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function. (Defined by Enumerable.) | |

SkipWhile(Of T)(Func(Of T, Int32, Boolean)) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Decimal)) | Overloaded. Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Decimal)) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Decimal))) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Double)) | Overloaded. Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Double)) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Double))) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Int32)) | Overloaded. Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Int64)) | Overloaded. Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Single)) | Overloaded. Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Int32)) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Int64)) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Int32))) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Int64))) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Nullable(Of Single))) | Overloaded. (Defined by Enumerable.) | |

Sum(Of T)(Func(Of T, Single)) | Overloaded. (Defined by Enumerable.) | |

Take(Of T)(Int32) | Overloaded. Returns a specified number of contiguous elements from the start of a sequence. (Defined by Enumerable.) | |

Take(Of T)(Int32) | Overloaded. (Defined by Enumerable.) | |

TakeWhile(Of T)(Func(Of T, Boolean)) | Overloaded. Returns elements from a sequence as long as a specified condition is true. (Defined by Enumerable.) | |

TakeWhile(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

TakeWhile(Of T)(Func(Of T, Int32, Boolean)) | Overloaded. Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function. (Defined by Enumerable.) | |

TakeWhile(Of T)(Func(Of T, Int32, Boolean)) | Overloaded. (Defined by Enumerable.) | |

ToArray(Of T) | Overloaded. Creates an array from a IEnumerable(Of T). (Defined by Enumerable.) | |

ToArray(Of T) | Overloaded. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey)(Func(Of T, TKey)) | Overloaded. Creates a Dictionary(Of TKey, TValue) from an IEnumerable(Of T) according to a specified key selector function. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey)(Func(Of T, TKey)) | Overloaded. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey)(Func(Of T, TKey), IEqualityComparer(Of TKey)) | Overloaded. Creates a Dictionary(Of TKey, TValue) from an IEnumerable(Of T) according to a specified key selector function and key comparer. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey)(Func(Of T, TKey), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement)) | Overloaded. Creates a Dictionary(Of TKey, TValue) from an IEnumerable(Of T) according to specified key selector and element selector functions. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement)) | Overloaded. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement), IEqualityComparer(Of TKey)) | Overloaded. Creates a Dictionary(Of TKey, TValue) from an IEnumerable(Of T) according to a specified key selector function, a comparer, and an element selector function. (Defined by Enumerable.) | |

ToDictionary(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

ToList(Of T) | Overloaded. Creates a List(Of T) from an IEnumerable(Of T). (Defined by Enumerable.) | |

ToList(Of T) | Overloaded. (Defined by Enumerable.) | |

ToLookup(Of T, TKey)(Func(Of T, TKey)) | Overloaded. Creates a Lookup(Of TKey, TElement) from an IEnumerable(Of T) according to a specified key selector function. (Defined by Enumerable.) | |

ToLookup(Of T, TKey)(Func(Of T, TKey)) | Overloaded. (Defined by Enumerable.) | |

ToLookup(Of T, TKey)(Func(Of T, TKey), IEqualityComparer(Of TKey)) | Overloaded. Creates a Lookup(Of TKey, TElement) from an IEnumerable(Of T) according to a specified key selector function and key comparer. (Defined by Enumerable.) | |

ToLookup(Of T, TKey)(Func(Of T, TKey), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

ToLookup(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement)) | Overloaded. Creates a Lookup(Of TKey, TElement) from an IEnumerable(Of T) according to specified key selector and element selector functions. (Defined by Enumerable.) | |

ToLookup(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement)) | Overloaded. (Defined by Enumerable.) | |

ToLookup(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement), IEqualityComparer(Of TKey)) | Overloaded. Creates a Lookup(Of TKey, TElement) from an IEnumerable(Of T) according to a specified key selector function, a comparer and an element selector function. (Defined by Enumerable.) | |

ToLookup(Of T, TKey, TElement)(Func(Of T, TKey), Func(Of T, TElement), IEqualityComparer(Of TKey)) | Overloaded. (Defined by Enumerable.) | |

Union(Of T)(IEnumerable(Of T)) | Overloaded. Produces the set union of two sequences by using the default equality comparer. (Defined by Enumerable.) | |

Union(Of T)(IEnumerable(Of T)) | Overloaded. (Defined by Enumerable.) | |

Union(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. Produces the set union of two sequences by using a specified IEqualityComparer(Of T). (Defined by Enumerable.) | |

Union(Of T)(IEnumerable(Of T), IEqualityComparer(Of T)) | Overloaded. (Defined by Enumerable.) | |

Where(Of T)(Func(Of T, Boolean)) | Overloaded. Filters a sequence of values based on a predicate. (Defined by Enumerable.) | |

Where(Of T)(Func(Of T, Boolean)) | Overloaded. (Defined by Enumerable.) | |

Where(Of T)(Func(Of T, Int32, Boolean)) | Overloaded. Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function. (Defined by Enumerable.) | |

Where(Of T)(Func(Of T, Int32, Boolean)) | Overloaded. (Defined by Enumerable.) | |

Zip(Of T, TSecond, TResult)(IEnumerable(Of TSecond), Func(Of T, TSecond, TResult)) | Overloaded. Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results. (Defined by Enumerable.) | |

Zip(Of T, TSecond, TResult)(IEnumerable(Of TSecond), Func(Of T, TSecond, TResult)) | Overloaded. (Defined by Enumerable.) |

Name | Description | |
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ICollection(Of T).Add | Adds an item to an ICollection(Of T) object. | |

ICollection(Of T).IsReadOnly | Gets a value indicating whether a collection is read-only. | |

IEnumerable(Of T).GetEnumerator | Returns an enumerator that iterates through a collection. | |

IEnumerable.GetEnumerator | Returns an enumerator that iterates through a collection. |

Note |
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To view the .NET Framework source code for this type, see the Reference Source. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructions. |

The HashSet(Of T) class provides high-performance set operations. A set is a collection that contains no duplicate elements, and whose elements are in no particular order.

The capacity of a HashSet(Of T) object is the number of elements that the object can hold. A HashSet(Of T) object's capacity automatically increases as elements are added to the object.

The HashSet(Of T) class is based on the model of mathematical sets and provides high-performance set operations similar to accessing the keys of the Dictionary(Of TKey, TValue) or Hashtable collections. In simple terms, the HashSet(Of T) class can be thought of as a Dictionary(Of TKey, TValue) collection without values.

A HashSet(Of T) collection is not sorted and cannot contain duplicate elements. If order or element duplication is more important than performance for your application, consider using the List(Of T) class together with the Sort method.

HashSet(Of T) provides many mathematical set operations, such as set addition (unions) and set subtraction. The following table lists the provided HashSet(Of T) operations and their mathematical equivalents.

HashSet(Of T) operation | Mathematical equivalent |
---|---|

Union or set addition | |

Intersection | |

Set subtraction | |

Symmetric difference |

In addition to the listed set operations, the HashSet(Of T) class also provides methods for determining set equality, overlap of sets, and whether a set is a subset or superset of another set.

For very large HashSet(Of T) objects, you can increase the maximum capacity to 2 billion elements on a 64-bit system by setting the enabled attribute of the gcAllowVeryLargeObjects configuration element to true in the run-time environment.

Starting with the .NET Framework 4, the HashSet(Of T) class implements the ISet(Of T) interface.

### HashSet and LINQ Set Operations

LINQ provides access to the Distinct, Union, Intersect and Except set operations on any data source that implements the IEnumerable or IQueryable interfaces. HashSet(Of T) provides a larger and more robust collection of set operations. For example, HashSet(Of T) provides comparisons such as IsSubsetOf and IsSupersetOf.

The primary difference between LINQ set operations and HashSet(Of T) operations is that LINQ set operations always return a new IEnumerable(Of T) collection, whereas the HashSet(Of T) equivalent methods modify the current collection.

Typically, if you must create a new set or if your application needs access only to the provided set operations, using LINQ set operations on any IEnumerable(Of T) collection or array will be sufficient. However, if your application requires access to additional set operations, or if it is not desirable or necessary to create a new collection, use the HashSet(Of T) class.

The following table shows the HashSet(Of T) operations and their equivalent LINQ set operations.

HashSet(Of T) operation | LINQ equivalent |
---|---|

Not provided. | |

Not provided. | |

Not provided. | |

Not provided. | |

Not provided. | |

Not provided. | |

Not provided. | |

Not provided. |

Note |
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The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: MayLeakOnAbort. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes. |

The following example demonstrates how to merge two disparate sets. This example creates two HashSet(Of T) objects, and populates them with even and odd numbers, respectively. A third HashSet(Of T) object is created from the set that contains the even numbers. The example then calls the UnionWith method, which adds the odd number set to the third set.

Imports System Imports System.Collections.Generic Class Program Shared Sub Main() Dim evenNumbers As HashSet(Of Integer) = New HashSet(Of Integer)() Dim oddNumbers As HashSet(Of Integer) = New HashSet(Of Integer)() For i As Integer = 0 To 4 ' Populate evenNumbers with only even numbers. evenNumbers.Add(i * 2) ' Populate oddNumbers with only odd numbers. oddNumbers.Add((i * 2) + 1) Next i Console.Write("evenNumbers contains {0} elements: ", evenNumbers.Count) DisplaySet(evenNumbers) Console.Write("oddNumbers contains {0} elements: ", oddNumbers.Count) DisplaySet(oddNumbers) ' Create a new HashSet populated with even numbers. Dim numbers As HashSet(Of Integer) = New HashSet(Of Integer)(evenNumbers) Console.WriteLine("numbers UnionWith oddNumbers...") numbers.UnionWith(oddNumbers) Console.Write("numbers contains {0} elements: ", numbers.Count) DisplaySet(numbers) End Sub Private Shared Sub DisplaySet(ByVal coll As HashSet(Of Integer)) Console.Write("{") For Each i As Integer In coll Console.Write(" {0}", i) Next i Console.WriteLine(" }") End Sub End Class ' This example produces output similar to the following: ' evenNumbers contains 5 elements: { 0 2 4 6 8 } ' oddNumbers contains 5 elements: { 1 3 5 7 9 } ' numbers UnionWith oddNumbers... ' numbers contains 10 elements: { 0 2 4 6 8 1 3 5 7 9 }