Enumerable.Sum 方法

定义

命名空间:

System.Linq

程序集:

netstandard.dll, System.Linq.dll

计算数值序列的总和。

重载

名称	说明
Sum(IEnumerable<Decimal>)	计算一系列 Decimal 值的总和。
Sum(IEnumerable<Double>)	计算一系列 Double 值的总和。
Sum(IEnumerable<Int32>)	计算一系列 Int32 值的总和。
Sum(IEnumerable<Int64>)	计算一系列 Int64 值的总和。
Sum(IEnumerable<Nullable<Decimal>>)	计算可为 null 的 Decimal 值序列的总和。
Sum(IEnumerable<Nullable<Double>>)	计算可为 null 的 Double 值序列的总和。
Sum(IEnumerable<Nullable<Int32>>)	计算可为 null 的 Int32 值序列的总和。
Sum(IEnumerable<Nullable<Int64>>)	计算可为 null 的 Int64 值序列的总和。
Sum(IEnumerable<Nullable<Single>>)	计算可为 null 的 Single 值序列的总和。
Sum(IEnumerable<Single>)	计算一系列 Single 值的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>)	计算通过对输入序列的每个元素调用转换函数获得的 Single 值序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>)	计算通过对输入序列的每个元素调用转换函数获取的可为 null Single 值的序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>)	计算通过对输入序列的每个元素调用转换函数获取的可为 null Int64 值的序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>)	计算通过对输入序列的每个元素调用转换函数获取的可为 null Int32 值的序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>)	计算通过对输入序列的每个元素调用转换函数获取的可为 null Double 值的序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int32>)	计算通过对输入序列的每个元素调用转换函数获得的 Int32 值序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int64>)	计算通过对输入序列的每个元素调用转换函数获得的 Int64 值序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>)	计算通过对输入序列的每个元素调用转换函数获得的 Double 值序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>)	计算通过对输入序列的每个元素调用转换函数获得的 Decimal 值序列的总和。
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>)	计算通过对输入序列的每个元素调用转换函数获取的可为 null Decimal 值的序列的总和。

Sum(IEnumerable<Decimal>)

Source:

Sum.cs

计算一系列 Decimal 值的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static System::Decimal Sum(System::Collections::Generic::IEnumerable<System::Decimal> ^ source);

public static decimal Sum(this System.Collections.Generic.IEnumerable<decimal> source);

static member Sum : seq<decimal> -> decimal

<Extension()>
Public Function Sum (source As IEnumerable(Of Decimal)) As Decimal

参数

source

IEnumerable<Decimal>

要计算其总和的值序列 Decimal 。

返回

Decimal

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Decimal.MaxValue。

注解

如果Sum(IEnumerable<Decimal>)不包含任何元素，则source该方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Double>)

Source:

Sum.cs

计算一系列 Double 值的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static double Sum(System::Collections::Generic::IEnumerable<double> ^ source);

public static double Sum(this System.Collections.Generic.IEnumerable<double> source);

static member Sum : seq<double> -> double

<Extension()>
Public Function Sum (source As IEnumerable(Of Double)) As Double

参数

source

IEnumerable<Double>

要计算其总和的值序列 Double 。

返回

Double

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Double.MaxValue。

注解

如果 source 不包含任何元素，则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Int32>)

Source:

Sum.cs

计算一系列 Int32 值的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static int Sum(System::Collections::Generic::IEnumerable<int> ^ source);

public static int Sum(this System.Collections.Generic.IEnumerable<int> source);

static member Sum : seq<int> -> int

<Extension()>
Public Function Sum (source As IEnumerable(Of Integer)) As Integer

参数

source

IEnumerable<Int32>

要计算其总和的值序列 Int32 。

返回

Int32

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Int32.MaxValue。

注解

如果 source 不包含任何元素，则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Int64>)

Source:

Sum.cs

计算一系列 Int64 值的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static long Sum(System::Collections::Generic::IEnumerable<long> ^ source);

public static long Sum(this System.Collections.Generic.IEnumerable<long> source);

static member Sum : seq<int64> -> int64

<Extension()>
Public Function Sum (source As IEnumerable(Of Long)) As Long

参数

source

IEnumerable<Int64>

要计算其总和的值序列 Int64 。

返回

Int64

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Int64.MaxValue。

注解

如果 source 不包含任何元素，则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Nullable<Decimal>>)

Source:

Sum.cs

计算可为 null 的 Decimal 值序列的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static Nullable<System::Decimal> Sum(System::Collections::Generic::IEnumerable<Nullable<System::Decimal>> ^ source);

public static decimal? Sum(this System.Collections.Generic.IEnumerable<decimal?> source);

static member Sum : seq<Nullable<decimal>> -> Nullable<decimal>

<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Decimal))) As Nullable(Of Decimal)

参数

source

IEnumerable<Nullable<Decimal>>

要计算其总和的可为 Decimal null 值序列。

返回

Nullable<Decimal>

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Decimal.MaxValue。

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Nullable<Double>>)

Source:

Sum.cs

计算可为 null 的 Double 值序列的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static Nullable<double> Sum(System::Collections::Generic::IEnumerable<Nullable<double>> ^ source);

public static double? Sum(this System.Collections.Generic.IEnumerable<double?> source);

static member Sum : seq<Nullable<double>> -> Nullable<double>

<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Double))) As Nullable(Of Double)

参数

source

IEnumerable<Nullable<Double>>

要计算其总和的可为 Double null 值序列。

返回

Nullable<Double>

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Double.MaxValue。

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Nullable<Int32>>)

Source:

Sum.cs

计算可为 null 的 Int32 值序列的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static Nullable<int> Sum(System::Collections::Generic::IEnumerable<Nullable<int>> ^ source);

public static int? Sum(this System.Collections.Generic.IEnumerable<int?> source);

static member Sum : seq<Nullable<int>> -> Nullable<int>

<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Integer))) As Nullable(Of Integer)

参数

source

IEnumerable<Nullable<Int32>>

要计算其总和的可为 Int32 null 值序列。

返回

Nullable<Int32>

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Int32.MaxValue。

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Nullable<Int64>>)

Source:

Sum.cs

计算可为 null 的 Int64 值序列的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static Nullable<long> Sum(System::Collections::Generic::IEnumerable<Nullable<long>> ^ source);

public static long? Sum(this System.Collections.Generic.IEnumerable<long?> source);

static member Sum : seq<Nullable<int64>> -> Nullable<int64>

<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Long))) As Nullable(Of Long)

参数

source

IEnumerable<Nullable<Int64>>

要计算其总和的可为 Int64 null 值序列。

返回

Nullable<Int64>

序列中值的总和。

例外

ArgumentNullException

source 是 null。

OverflowException

总和大于 Int64.MaxValue。

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Nullable<Single>>)

Source:

Sum.cs

计算可为 null 的 Single 值序列的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static Nullable<float> Sum(System::Collections::Generic::IEnumerable<Nullable<float>> ^ source);

public static float? Sum(this System.Collections.Generic.IEnumerable<float?> source);

static member Sum : seq<Nullable<single>> -> Nullable<single>

<Extension()>
Public Function Sum (source As IEnumerable(Of Nullable(Of Single))) As Nullable(Of Single)

参数

source

IEnumerable<Nullable<Single>>

要计算其总和的可为 Single null 值序列。

返回

Nullable<Single>

序列中值的总和。

例外

ArgumentNullException

source 是 null。

示例

下面的代码示例演示如何用于 Sum(IEnumerable<Nullable<Single>>) 对序列的值求和。

float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };

float? sum = points.Sum();

Console.WriteLine("Total points earned: {0}", sum);

/*
 This code produces the following output:

 Total points earned: 311.39
*/

' Create an array of Nullable Single values.
Dim points() As Nullable(Of Single) =
{Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

' Get the sum of values in the list.
Dim sum As Nullable(Of Single) = points.Sum()

' Display the output.
Console.WriteLine($"Total points earned: {sum}")

' This code produces the following output:
'
' Total points earned: 311.39

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum(IEnumerable<Single>)

Source:

Sum.cs

计算一系列 Single 值的总和。

public:
[System::Runtime::CompilerServices::Extension]
 static float Sum(System::Collections::Generic::IEnumerable<float> ^ source);

public static float Sum(this System.Collections.Generic.IEnumerable<float> source);

static member Sum : seq<single> -> single

<Extension()>
Public Function Sum (source As IEnumerable(Of Single)) As Single

参数

source

IEnumerable<Single>

要计算其总和的值序列 Single 。

返回

Single

序列中值的总和。

例外

ArgumentNullException

source 是 null。

示例

下面的代码示例演示如何用于 Sum(IEnumerable<Single>) 对序列的值求和。

List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };

float sum = numbers.Sum();

Console.WriteLine("The sum of the numbers is {0}.", sum);

/*
 This code produces the following output:

 The sum of the numbers is 635.13.
*/

' Create a list of Single values.
Dim numbers As New List(Of Single)(New Single() _
                               {43.68F, 1.25F, 583.7F, 6.5F})

' Get the sum of values in the list.
Dim sum As Single = numbers.Sum()

' Display the output.
Console.WriteLine($"The sum of the numbers is {sum}")

' This code produces the following output:
'
' The sum of the numbers is 635.13

注解

如果 source 不包含任何元素，则此方法返回零。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获得的 Single 值序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static float Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, float> ^ selector);

public static float Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,float> selector);

static member Sum : seq<'Source> * Func<'Source, single> -> single

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Single)) As Single

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Single>

要应用于每个元素的转换函数。

返回

Single

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

如果Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>)不包含任何元素，则source该方法返回零。

如果你提供一个函数，selector则可将此方法应用于任意值的序列，该函数专门source将成员投影Single到数值类型中。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获取的可为 null Single 值的序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static Nullable<float> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<float>> ^ selector);

public static float? Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,float?> selector);

static member Sum : seq<'Source> * Func<'Source, Nullable<single>> -> Nullable<single>

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Single))) As Nullable(Of Single)

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Nullable<Single>>

要应用于每个元素的转换函数。

返回

Nullable<Single>

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

如果提供函数 selector，可将 source 的成员投影到数值类型中（特别是 C# 中的 Nullable<Single> 或 Visual Basic 中的 Nullable(Of Single)）时，可以将此方法应用于任意值序列。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获取的可为 null Int64 值的序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static Nullable<long> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<long>> ^ selector);

public static long? Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,long?> selector);

static member Sum : seq<'Source> * Func<'Source, Nullable<int64>> -> Nullable<int64>

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Long))) As Nullable(Of Long)

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Nullable<Int64>>

要应用于每个元素的转换函数。

返回

Nullable<Int64>

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Int64.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

如果提供一个函数（selector）将 source的成员投影到数值类型中（特别是 C# 中的 Nullable<Int64>）或 Nullable(Of Int64) Visual Basic 中，则可以将此方法应用于任意值序列

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获取的可为 null Int32 值的序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static Nullable<int> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<int>> ^ selector);

public static int? Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,int?> selector);

static member Sum : seq<'Source> * Func<'Source, Nullable<int>> -> Nullable<int>

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Integer))) As Nullable(Of Integer)

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Nullable<Int32>>

要应用于每个元素的转换函数。

返回

Nullable<Int32>

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Int32.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

如果提供函数 selector，可将 source 的成员投影到数值类型中（特别是 C# 中的 Nullable<Int32> 或 Visual Basic 中的 Nullable(Of Int32)）时，可以将此方法应用于任意值序列。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获取的可为 null Double 值的序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static Nullable<double> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<double>> ^ selector);

public static double? Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,double?> selector);

static member Sum : seq<'Source> * Func<'Source, Nullable<double>> -> Nullable<double>

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Double))) As Nullable(Of Double)

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Nullable<Double>>

要应用于每个元素的转换函数。

返回

Nullable<Double>

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Double.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

如果提供函数 selector，可将 source 的成员投影到数值类型中（特别是 C# 中的 Nullable<Double> 或 Visual Basic 中的 Nullable(Of Double)）时，可以将此方法应用于任意值序列。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int32>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获得的 Int32 值序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static int Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, int> ^ selector);

public static int Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,int> selector);

static member Sum : seq<'Source> * Func<'Source, int> -> int

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Integer)) As Integer

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Int32>

要应用于每个元素的转换函数。

返回

Int32

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Int32.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

如果 source 不包含任何元素，则此方法返回零。

如果你提供一个函数，selector则可将此方法应用于任意值的序列，该函数专门source将成员投影Int32到数值类型中。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int64>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获得的 Int64 值序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static long Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, long> ^ selector);

public static long Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,long> selector);

static member Sum : seq<'Source> * Func<'Source, int64> -> int64

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Long)) As Long

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Int64>

要应用于每个元素的转换函数。

返回

Int64

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Int64.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

如果 source 不包含任何元素，则此方法返回零。

如果你提供一个函数，selector则可将此方法应用于任意值的序列，该函数专门source将成员投影Int64到数值类型中。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获得的 Double 值序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static double Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, double> ^ selector);

public static double Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,double> selector);

static member Sum : seq<'Source> * Func<'Source, double> -> double

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Double)) As Double

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Double>

要应用于每个元素的转换函数。

返回

Double

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Double.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

如果 source 不包含任何元素，则此方法返回零。

如果你提供一个函数，selector则可将此方法应用于任意值的序列，该函数专门source将成员投影Double到数值类型中。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获得的 Decimal 值序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Decimal Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, System::Decimal> ^ selector);

public static decimal Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,decimal> selector);

static member Sum : seq<'Source> * Func<'Source, decimal> -> decimal

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Decimal)) As Decimal

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Decimal>

要应用于每个元素的转换函数。

返回

Decimal

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Decimal.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

如果 source 不包含任何元素，则此方法返回零。

如果你提供一个函数，selector则可将此方法应用于任意值的序列，该函数专门source将成员投影Decimal到数值类型中。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）

Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>)

Source:

Sum.cs

计算通过对输入序列的每个元素调用转换函数获取的可为 null Decimal 值的序列的总和。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static Nullable<System::Decimal> Sum(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, Nullable<System::Decimal>> ^ selector);

public static decimal? Sum<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,decimal?> selector);

static member Sum : seq<'Source> * Func<'Source, Nullable<decimal>> -> Nullable<decimal>

<Extension()>
Public Function Sum(Of TSource) (source As IEnumerable(Of TSource), selector As Func(Of TSource, Nullable(Of Decimal))) As Nullable(Of Decimal)

类型参数

TSource

的元素 source的类型。

参数

source

IEnumerable<TSource>

用于计算总和的值序列。

selector

Func<TSource,Nullable<Decimal>>

要应用于每个元素的转换函数。

返回

Nullable<Decimal>

投影值的总和。

例外

ArgumentNullException

source 或 selector 为 null.

OverflowException

总和大于 Decimal.MaxValue。

示例

下面的代码示例演示如何用于 Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>) 对序列的投影值求和。

注释

此代码示例使用与本文介绍的特定重载不同的方法的重载。 若要将示例扩展到本文介绍的重载，请更改函数的 selector 正文。

class Package
{
    public string Company { get; set; }
    public double Weight { get; set; }
}

public static void SumEx1()
{
    List<Package> packages =
        new List<Package>
            { new Package { Company = "Coho Vineyard", Weight = 25.2 },
              new Package { Company = "Lucerne Publishing", Weight = 18.7 },
              new Package { Company = "Wingtip Toys", Weight = 6.0 },
              new Package { Company = "Adventure Works", Weight = 33.8 } };

    double totalWeight = packages.Sum(pkg => pkg.Weight);

    Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
 This code produces the following output:

 The total weight of the packages is: 83.7
*/

Structure Package
    Public Company As String
    Public Weight As Double
End Structure

Sub SumEx1()
    ' Create a list of Package values.
    Dim packages As New List(Of Package)(New Package() _
     {New Package With {.Company = "Coho Vineyard", .Weight = 25.2},
      New Package With {.Company = "Lucerne Publishing", .Weight = 18.7},
      New Package With {.Company = "Wingtip Toys", .Weight = 6.0},
      New Package With {.Company = "Adventure Works", .Weight = 33.8}})

    ' Sum the values from each item's Weight property.
    Dim totalWeight As Double = packages.Sum(Function(pkg) _
                                             pkg.Weight)

    ' Display the result.
    Console.WriteLine($"The total weight of the packages is: {totalWeight}")
End Sub

' This code produces the following output:
'
' The total weight of the packages is: 83.7

注解

source null从求和计算中排除的项。 如果 source 不包含任何元素或所有元素， null则此方法返回零。

如果提供函数 selector，可将 source 的成员投影到数值类型中（特别是 C# 中的 Nullable<Decimal> 或 Visual Basic 中的 Nullable(Of Decimal)）时，可以将此方法应用于任意值序列。

在Visual Basic查询表达式语法中，Aggregate Into Sum() 子句转换为调用 Sum。

另请参阅

• Aggregate 子句（Visual Basic）