Enumerable.ToDictionary 方法
重要
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根據指定的索引鍵相等比較子，從列舉建立字典。
public:
generic <typename TKey, typename TValue>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TValue> ^ ToDictionary(System::Collections::Generic::IEnumerable<ValueTuple<TKey, TValue>> ^ source, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);C#
public static System.Collections.Generic.Dictionary<TKey,TValue> ToDictionary<TKey,TValue> (this System.Collections.Generic.IEnumerable<(TKey Key, TValue Value)> source, System.Collections.Generic.IEqualityComparer<TKey>? comparer);static member ToDictionary : seq<ValueTuple<'Key, 'Value>> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Generic.Dictionary<'Key, 'Value><Extension()>
Public Function ToDictionary(Of TKey, TValue) (source As IEnumerable(Of ValueTuple(Of TKey, TValue)), comparer As IEqualityComparer(Of TKey)) As Dictionary(Of TKey, TValue)類型參數
- TKey
專案的 source索引鍵型別。
- TValue
專案的 source值型別。
參數
- source
- IEnumerable<ValueTuple<TKey,TValue>>
要從中建立字典的列舉。
- comparer
- IEqualityComparer<TKey>
比較索引鍵的相等比較子。
傳回
字典，其中包含的 source索引鍵和值。
例外狀況
source 是 null 參考。
source 包含一或多個重複的索引鍵。
備註
如果 為 comparernull，則會使用預設相等比較子 Default 來比較索引鍵。
適用於
.NET 9 和 .NET 8
| 產品 | 版本 |
|---|---|
| .NET | 8, 9 |
根據指定的索引鍵比較子，從列舉建立字典。
public:
generic <typename TKey, typename TValue>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TValue> ^ ToDictionary(System::Collections::Generic::IEnumerable<System::Collections::Generic::KeyValuePair<TKey, TValue>> ^ source, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);C#
public static System.Collections.Generic.Dictionary<TKey,TValue> ToDictionary<TKey,TValue> (this System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey,TValue>> source, System.Collections.Generic.IEqualityComparer<TKey>? comparer);static member ToDictionary : seq<System.Collections.Generic.KeyValuePair<'Key, 'Value>> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Generic.Dictionary<'Key, 'Value><Extension()>
Public Function ToDictionary(Of TKey, TValue) (source As IEnumerable(Of KeyValuePair(Of TKey, TValue)), comparer As IEqualityComparer(Of TKey)) As Dictionary(Of TKey, TValue)類型參數
- TKey
專案的 source索引鍵型別。
- TValue
專案的 source值型別。
參數
- source
- IEnumerable<KeyValuePair<TKey,TValue>>
要從中建立字典的列舉。
- comparer
- IEqualityComparer<TKey>
比較索引鍵的相等比較子。
傳回
字典，其中包含的 source索引鍵和值。
例外狀況
source 是 null 參考。
source 包含一或多個重複的索引鍵。
備註
如果 為 comparernull，則會使用預設相等比較子 Default 來比較索引鍵。
適用於
.NET 9 和 .NET 8
| 產品 | 版本 |
|---|---|
| .NET | 8, 9 |
根據索引鍵類型的預設比較子，從列舉建立字典。
public:
generic <typename TKey, typename TValue>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TValue> ^ ToDictionary(System::Collections::Generic::IEnumerable<System::Collections::Generic::KeyValuePair<TKey, TValue>> ^ source);C#
public static System.Collections.Generic.Dictionary<TKey,TValue> ToDictionary<TKey,TValue> (this System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<TKey,TValue>> source);static member ToDictionary : seq<System.Collections.Generic.KeyValuePair<'Key, 'Value>> -> System.Collections.Generic.Dictionary<'Key, 'Value><Extension()>
Public Function ToDictionary(Of TKey, TValue) (source As IEnumerable(Of KeyValuePair(Of TKey, TValue))) As Dictionary(Of TKey, TValue)類型參數
- TKey
專案的 source索引鍵型別。
- TValue
專案的 source值型別。
參數
- source
- IEnumerable<KeyValuePair<TKey,TValue>>
要從中建立字典的列舉。
傳回
字典，其中包含的 source 索引鍵和值，並使用索引鍵類型的預設比較子。
例外狀況
source 是 null 參考。
source 包含一或多個重複的索引鍵。
適用於
.NET 9 和 .NET 8
| 產品 | 版本 |
|---|---|
| .NET | 8, 9 |
根據索引鍵類型的預設比較子，從列舉建立字典。
public:
generic <typename TKey, typename TValue>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TValue> ^ ToDictionary(System::Collections::Generic::IEnumerable<ValueTuple<TKey, TValue>> ^ source);C#
public static System.Collections.Generic.Dictionary<TKey,TValue> ToDictionary<TKey,TValue> (this System.Collections.Generic.IEnumerable<(TKey Key, TValue Value)> source);static member ToDictionary : seq<ValueTuple<'Key, 'Value>> -> System.Collections.Generic.Dictionary<'Key, 'Value><Extension()>
Public Function ToDictionary(Of TKey, TValue) (source As IEnumerable(Of ValueTuple(Of TKey, TValue))) As Dictionary(Of TKey, TValue)類型參數
- TKey
專案的 source索引鍵型別。
- TValue
專案的 source值型別。
參數
- source
- IEnumerable<ValueTuple<TKey,TValue>>
要從中建立字典的列舉。
傳回
包含索引 source 鍵和值的字典，並使用索引鍵類型的預設比較子。
例外狀況
source 是 null 參考。
source 包含一或多個重複的索引鍵。
適用於
.NET 9 和 .NET 8
| 產品 | 版本 |
|---|---|
| .NET | 8, 9 |
ToDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>)
根據指定的索引鍵選取器和項目選取器函式，從 Dictionary<TKey,TValue> 建立 IEnumerable<T>。
public:
generic <typename TSource, typename TKey, typename TElement>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TElement> ^ ToDictionary(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector);C#
public static System.Collections.Generic.Dictionary<TKey,TElement> ToDictionary<TSource,TKey,TElement> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector);static member ToDictionary : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> -> System.Collections.Generic.Dictionary<'Key, 'Element><Extension()>
Public Function ToDictionary(Of TSource, TKey, TElement) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), elementSelector As Func(Of TSource, TElement)) As Dictionary(Of TKey, TElement)類型參數
- TSource
source 項目的類型。
- TKey
keySelector 所傳回之索引鍵的型別。
- TElement
elementSelector 所傳回值的型別。
參數
- source
- IEnumerable<TSource>
用來建立 Dictionary<TKey,TValue> 的來源 IEnumerable<T>。
- keySelector
- Func<TSource,TKey>
用來從各個項目擷取索引鍵的函式。
- elementSelector
- Func<TSource,TElement>
用來從每個項目產生結果項目值的轉換函式。
傳回
Dictionary<TKey,TElement>
Dictionary<TKey,TValue>，包含從輸入序列選取之 TElement 類型的值。
例外狀況
keySelector 產生兩個項目的重複索引鍵。
備註
方法 ToDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>) 會使用預設相等比較子 Default 來比較索引鍵。
適用於
.NET 9 和其他版本
| 產品 | 版本 |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
| .NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
ToDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>)
根據指定的索引鍵選取器函式、比較子和項目選取器函式，從 Dictionary<TKey,TValue> 建立 IEnumerable<T>。
public:
generic <typename TSource, typename TKey, typename TElement>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TElement> ^ ToDictionary(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, Func<TSource, TElement> ^ elementSelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);C#
public static System.Collections.Generic.Dictionary<TKey,TElement> ToDictionary<TSource,TKey,TElement> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);C#
public static System.Collections.Generic.Dictionary<TKey,TElement> ToDictionary<TSource,TKey,TElement> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, Func<TSource,TElement> elementSelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);static member ToDictionary : seq<'Source> * Func<'Source, 'Key> * Func<'Source, 'Element> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Generic.Dictionary<'Key, 'Element><Extension()>
Public Function ToDictionary(Of TSource, TKey, TElement) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), elementSelector As Func(Of TSource, TElement), comparer As IEqualityComparer(Of TKey)) As Dictionary(Of TKey, TElement)類型參數
- TSource
source 項目的類型。
- TKey
keySelector 所傳回之索引鍵的型別。
- TElement
elementSelector 所傳回值的型別。
參數
- source
- IEnumerable<TSource>
用來建立 Dictionary<TKey,TValue> 的來源 IEnumerable<T>。
- keySelector
- Func<TSource,TKey>
用來從各個項目擷取索引鍵的函式。
- elementSelector
- Func<TSource,TElement>
用來從每個項目產生結果項目值的轉換函式。
- comparer
- IEqualityComparer<TKey>
用來比較金鑰的 IEqualityComparer<T>。
傳回
Dictionary<TKey,TElement>
Dictionary<TKey,TValue>，包含從輸入序列選取之 TElement 類型的值。
例外狀況
keySelector 產生兩個項目的重複索引鍵。
備註
如果 為 comparernull，則會使用預設相等比較子 Default 來比較索引鍵。
適用於
.NET 9 和其他版本
| 產品 | 版本 |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
| .NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
根據指定的索引鍵選擇器函式，從 Dictionary<TKey,TValue> 建立 IEnumerable<T>。
public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TSource> ^ ToDictionary(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector);C#
public static System.Collections.Generic.Dictionary<TKey,TSource> ToDictionary<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector);static member ToDictionary : seq<'Source> * Func<'Source, 'Key> -> System.Collections.Generic.Dictionary<'Key, 'Source><Extension()>
Public Function ToDictionary(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey)) As Dictionary(Of TKey, TSource)類型參數
- TSource
source 項目的類型。
- TKey
keySelector 所傳回之索引鍵的型別。
參數
- source
- IEnumerable<TSource>
用來建立 Dictionary<TKey,TValue> 的來源 IEnumerable<T>。
- keySelector
- Func<TSource,TKey>
用來從各個項目擷取索引鍵的函式。
傳回
Dictionary<TKey,TSource>
包含索引鍵和值的 Dictionary<TKey,TValue>。 每個群組中的值與 source 中的順序相同。
例外狀況
keySelector 產生兩個項目的重複索引鍵。
範例
下列程式代碼範例示範如何使用 ToDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) 索引鍵選取器來建立 Dictionary<TKey,TValue> 。
C#
class Package
{
public string Company { get; set; }
public double Weight { get; set; }
public long TrackingNumber { get; set; }
}
public static void ToDictionaryEx1()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2, TrackingNumber = 89453312L },
new Package { Company = "Lucerne Publishing", Weight = 18.7, TrackingNumber = 89112755L },
new Package { Company = "Wingtip Toys", Weight = 6.0, TrackingNumber = 299456122L },
new Package { Company = "Adventure Works", Weight = 33.8, TrackingNumber = 4665518773L } };
// Create a Dictionary of Package objects,
// using TrackingNumber as the key.
Dictionary<long, Package> dictionary =
packages.ToDictionary(p => p.TrackingNumber);
foreach (KeyValuePair<long, Package> kvp in dictionary)
{
Console.WriteLine(
"Key {0}: {1}, {2} pounds",
kvp.Key,
kvp.Value.Company,
kvp.Value.Weight);
}
}
/*
This code produces the following output:
Key 89453312: Coho Vineyard, 25.2 pounds
Key 89112755: Lucerne Publishing, 18.7 pounds
Key 299456122: Wingtip Toys, 6 pounds
Key 4665518773: Adventure Works, 33.8 pounds
*/
Structure Package
Public Company As String
Public Weight As Double
Public TrackingNumber As Long
End Structure
Sub ToDictionaryEx1()
' Create a list of Package values.
Dim packages As New List(Of Package)(New Package() _
{New Package With
{.Company = "Coho Vineyard", .Weight = 25.2, .TrackingNumber = 89453312L},
New Package With
{.Company = "Lucerne Publishing", .Weight = 18.7, .TrackingNumber = 89112755L},
New Package With
{.Company = "Wingtip Toys", .Weight = 6.0, .TrackingNumber = 299456122L},
New Package With
{.Company = "Adventure Works", .Weight = 33.8, .TrackingNumber = 4665518773L}})
' Create a Dictionary that contains Package values,
' using TrackingNumber as the key.
Dim dict As Dictionary(Of Long, Package) =
packages.ToDictionary(Function(p) p.TrackingNumber)
' Display the results.
Dim output As New System.Text.StringBuilder
For Each kvp As KeyValuePair(Of Long, Package) In dict
output.AppendLine("Key " & kvp.Key & ": " &
kvp.Value.Company & ", " &
kvp.Value.Weight & " pounds")
Next
Console.WriteLine(output.ToString())
End Sub
' This code produces the following output:
'
' Key 89453312: Coho Vineyard, 25.2 pounds
' Key 89112755: Lucerne Publishing, 18.7 pounds
' Key 299456122: Wingtip Toys, 6 pounds
' Key 4665518773: Adventure Works, 33.8 pounds
備註
方法 ToDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>) 會使用預設相等比較子 Default 來比較索引鍵。
適用於
.NET 9 和其他版本
| 產品 | 版本 |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
| .NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
根據指定的索引鍵選取器函式和索引鍵比較子，從 Dictionary<TKey,TValue> 建立 IEnumerable<T>。
public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
static System::Collections::Generic::Dictionary<TKey, TSource> ^ ToDictionary(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, TKey> ^ keySelector, System::Collections::Generic::IEqualityComparer<TKey> ^ comparer);C#
public static System.Collections.Generic.Dictionary<TKey,TSource> ToDictionary<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer);C#
public static System.Collections.Generic.Dictionary<TKey,TSource> ToDictionary<TSource,TKey> (this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey>? comparer);static member ToDictionary : seq<'Source> * Func<'Source, 'Key> * System.Collections.Generic.IEqualityComparer<'Key> -> System.Collections.Generic.Dictionary<'Key, 'Source><Extension()>
Public Function ToDictionary(Of TSource, TKey) (source As IEnumerable(Of TSource), keySelector As Func(Of TSource, TKey), comparer As IEqualityComparer(Of TKey)) As Dictionary(Of TKey, TSource)類型參數
- TSource
source 項目的類型。
- TKey
keySelector 所傳回之索引鍵的型別。
參數
- source
- IEnumerable<TSource>
用來建立 Dictionary<TKey,TValue> 的來源 IEnumerable<T>。
- keySelector
- Func<TSource,TKey>
用來從各個項目擷取索引鍵的函式。
- comparer
- IEqualityComparer<TKey>
用來比較金鑰的 IEqualityComparer<T>。
傳回
Dictionary<TKey,TSource>
包含索引鍵和值的 Dictionary<TKey,TValue>。 每個群組中的值與 source 中的順序相同。
例外狀況
keySelector 產生兩個項目的重複索引鍵。
備註
如果 為 comparernull，則會使用預設相等比較子 Default 來比較索引鍵。
適用於
.NET 9 和其他版本
| 產品 | 版本 |
|---|---|
| .NET | Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9 |
| .NET Framework | 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1 |
| .NET Standard | 1.0, 1.1, 1.2, 1.3, 1.4, 1.6, 2.0, 2.1 |
| UWP | 10.0 |
