Single.Equals 方法

  • 参考

定义

命名空间:
System
程序集:
System.Runtime.dll
程序集:
mscorlib.dll
程序集:
netstandard.dll

返回一个值，该值指示 Single 的两个实例是否表示同一个值。

重载

Equals(Object)

返回一个值，该值指示此实例是否等于指定的对象。
Equals(Single)

返回一个值，该值指示此实例和指定的 Single 对象是否表示相同的值。

Equals(Object)

Source:
Single.cs
Source:
Single.cs
Source:
Single.cs

返回一个值，该值指示此实例是否等于指定的对象。

public:
 override bool Equals(System::Object ^ obj);
public override bool Equals (object obj);
public override bool Equals (object? obj);
override this.Equals : obj -> bool
Public Overrides Function Equals (obj As Object) As Boolean

参数

obj
Object

与此实例进行比较的对象。

返回

Boolean

如果 true 是 obj 的实例并且等于此实例的值，则为 Single；否则为 false。

示例

下面的代码示例演示 Equals 了 方法。

obj1 = (Single)500;

if ( a.Equals( obj1 ) )
{
   Console::WriteLine( "The value type and reference type values are equal." );
}

obj1 = (Single)500;
if (a.Equals(obj1)) {
    Console.WriteLine("The value type and reference type values are equal.");
}

let obj1 = single 500
if a.Equals obj1 then
    printfn "The value type and reference type values are equal."

Obj1 = CType(500, Single)

If A.Equals(Obj1) Then
    Console.WriteLine("The value type and reference type values are equal.")
End If

注解

Equals应谨慎使用 方法，因为由于两个值的精度不同，两个明显等效的值可能不相等。 以下示例报告 Single 值 .3333 和 Single 返回的 除以 1 除以 3 的值不相等。

// Initialize two floats with apparently identical values
float float1 = .33333f;
object float2 = 1/3;
// Compare them for equality
Console.WriteLine(float1.Equals(float2));    // displays false

// Initialize two floats with apparently identical values
let float1 = 0.33333f
let float2 = box (1f / 3f)
// Compare them for equality
printfn $"{float1.Equals float2}"    // displays false

' Initialize two singles with apparently identical values
Dim single1 As Single = .33333
Dim single2 As Object = 1/3
' Compare them for equality
Console.WriteLine(single1.Equals(single2))    ' displays False

建议的一种方法不是比较相等性，而是在两个值 (之间定义可接受的差差，例如) 值之一的 0.01%。 如果两个值之间的差异的绝对值小于或等于该边距，则差异可能是由于精度差异，因此，这些值可能相等。 以下示例使用此方法比较 .33333 和 1/3， Single 前一个代码示例发现两个值不相等。

// Initialize two floats with apparently identical values
float float1 = .33333f;
object float2 = (float) 1/3;
// Define the tolerance for variation in their values
float difference = Math.Abs(float1 * .0001f);

// Compare the values
// The output to the console indicates that the two values are equal
if (Math.Abs(float1 - (float) float2) <= difference)
   Console.WriteLine("float1 and float2 are equal.");
else
   Console.WriteLine("float1 and float2 are unequal.");

// Initialize two floats with apparently identical values
let float1 = 0.33333f
let float2 = box (1f / 3f)
// Define the tolerance for variation in their values
let difference = abs (float1 * 0.0001f)

// Compare the values
// The output to the console indicates that the two values are equal
if abs (float1 - (float2 :?> float32)) <= difference then
    printfn "float1 and float2 are equal."
else
    printfn "float1 and float2 are unequal."

' Initialize two singles with apparently identical values
Dim single1 As Single = .33333
Dim single2 As Object = 1/3
' Define the tolerance for variation in their values
Dim difference As Single = Math.Abs(single1 * .0001f)

' Compare the values
' The output to the console indicates that the two values are equal
If Math.Abs(single1 - CSng(single2)) <= difference Then
   Console.WriteLine("single1 and single2 are equal.")
Else
   Console.WriteLine("single1 and single2 are unequal.")
End If

在这种情况下，值相等。

注意

由于 Epsilon 定义其范围接近零的正值的最小表达式，因此差边距必须大于 Epsilon。 通常，它比 Epsilon大很多倍。

浮点数超出记录精度的精度特定于.NET Framework的实现和版本。 因此，两个特定数字的比较可能会在.NET Framework版本之间更改，因为数字内部表示形式的精度可能会更改。

调用方说明

编译器重载解析可能说明两 Equals(Object) 种方法重载的行为存在明显差异。 如果定义了 参数和 之间的Single隐式转换obj，并且参数未类型化为 Object，编译器可能会执行隐式转换并调用 Equals(Single) 方法。 否则，它们会调用 Equals(Object) 方法，如果其obj参数不是Single值，则该方法始终返回 false 。 以下示例演示了两个方法重载之间的行为差异。 对于除 Double Visual Basic 和 C# 中的 和 Double 之外Decimal的所有基元数值类型，第一个比较返回true是因为编译器自动执行扩展转换并调用 Equals(Single) 方法，而第二个比较返回false是因为编译器调用 Equals(Object) 方法。

using System;

public class Example
{
   static float value = 112;
   
   public static void Main()
   {
      byte byte1= 112;
      Console.WriteLine("value = byte1: {0,16}", value.Equals(byte1));
      TestObjectForEquality(byte1);

      short short1 = 112;
      Console.WriteLine("value = short1: {0,16}", value.Equals(short1));
      TestObjectForEquality(short1);

      int int1 = 112;
      Console.WriteLine("value = int1: {0,18}", value.Equals(int1));
      TestObjectForEquality(int1);

      long long1 = 112;
      Console.WriteLine("value = long1: {0,17}", value.Equals(long1));
      TestObjectForEquality(long1);
      
      sbyte sbyte1 = 112;
      Console.WriteLine("value = sbyte1: {0,16}", value.Equals(sbyte1));
      TestObjectForEquality(sbyte1);

      ushort ushort1 = 112;
      Console.WriteLine("value = ushort1: {0,16}", value.Equals(ushort1));
      TestObjectForEquality(ushort1);

      uint uint1 = 112;
      Console.WriteLine("value = uint1: {0,18}", value.Equals(uint1));
      TestObjectForEquality(uint1);

      ulong ulong1 = 112;
      Console.WriteLine("value = ulong1: {0,17}", value.Equals(ulong1));
      TestObjectForEquality(ulong1);
      
      decimal dec1 = 112m;
      Console.WriteLine("value = dec1: {0,21}", value.Equals(dec1));
      TestObjectForEquality(dec1);

      double dbl1 = 112;
      Console.WriteLine("value = dbl1: {0,20}", value.Equals(dbl1));
      TestObjectForEquality(dbl1);
   }

   private static void TestObjectForEquality(Object obj)
   {
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}\n",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj));
   }
}
// The example displays the following output:
//       value = byte1:             True
//       112 (Single) = 112 (Byte): False
//
//       value = short1:             True
//       112 (Single) = 112 (Int16): False
//
//       value = int1:               True
//       112 (Single) = 112 (Int32): False
//
//       value = long1:              True
//       112 (Single) = 112 (Int64): False
//
//       value = sbyte1:             True
//       112 (Single) = 112 (SByte): False
//
//       value = ushort1:             True
//       112 (Single) = 112 (UInt16): False
//
//       value = uint1:               True
//       112 (Single) = 112 (UInt32): False
//
//       value = ulong1:              True
//       112 (Single) = 112 (UInt64): False
//
//       value = dec1:                 False
//       112 (Single) = 112 (Decimal): False
//
//       value = dbl1:                False
//       112 (Single) = 112 (Double): False

let value = 112f

let testObjectForEquality (obj: obj) =
    printfn $"{value} ({value.GetType().Name}) = {obj} ({obj.GetType().Name}): {value.Equals obj}\n"

[<EntryPoint>]
let main _ =
    let byte1= 112uy
    printfn $"value = byte1: {value.Equals byte1,16}"
    testObjectForEquality byte1

    let short1 = 112s
    printfn $"value = short1: {value.Equals short1,16}"
    testObjectForEquality short1

    let int1 = 112
    printfn $"value = int1: {value.Equals int1,18}"
    testObjectForEquality int1

    let long1 = 112L
    printfn $"value = long1: {value.Equals long1,17}"
    testObjectForEquality long1
    
    let sbyte1 = 112y
    printfn $"value = sbyte1: {value.Equals sbyte1,16}"
    testObjectForEquality sbyte1

    let ushort1 = 112us
    printfn $"value = ushort1: {value.Equals ushort1,16}"
    testObjectForEquality ushort1

    let uint1 = 112u
    printfn $"value = uint1: {value.Equals uint1,18}"
    testObjectForEquality uint1

    let ulong1 = 112uL
    printfn $"value = ulong1: {value.Equals ulong1,17}"
    testObjectForEquality ulong1
    
    let dec1 = 112m
    printfn $"value = dec1: {value.Equals dec1,21}"
    testObjectForEquality dec1

    let dbl1 = 112.
    printfn $"value = dbl1: {value.Equals dbl1,20}"
    testObjectForEquality dbl1
    0

// The example displays the following output:
//       value = byte1:             True
//       112 (Single) = 112 (Byte): False
//
//       value = short1:             True
//       112 (Single) = 112 (Int16): False
//
//       value = int1:               True
//       112 (Single) = 112 (Int32): False
//
//       value = long1:              True
//       112 (Single) = 112 (Int64): False
//
//       value = sbyte1:             True
//       112 (Single) = 112 (SByte): False
//
//       value = ushort1:             True
//       112 (Single) = 112 (UInt16): False
//
//       value = uint1:               True
//       112 (Single) = 112 (UInt32): False
//
//       value = ulong1:              True
//       112 (Single) = 112 (UInt64): False
//
//       value = dec1:                 False
//       112 (Single) = 112 (Decimal): False
//
//       value = dbl1:                False
//       112 (Single) = 112 (Double): False

Module Example
   Dim value As Single = 112
   
   Public Sub Main()
      Dim byte1 As Byte = 112
      Console.WriteLine("value = byte1: {0,16}", value.Equals(byte1))
      TestObjectForEquality(byte1)
      
      Dim short1 As Short = 112
      Console.WriteLine("value = short1: {0,16}", value.Equals(short1))
      TestObjectForEquality(short1)

      Dim int1 As Integer = 112
      Console.WriteLine("value = int1: {0,18}", value.Equals(int1))
      TestObjectForEquality(int1)

      Dim long1 As Long = 112
      Console.WriteLine("value = long1: {0,17}", value.Equals(long1))
      TestObjectForEquality(long1)

      Dim sbyte1 As SByte = 112
      Console.WriteLine("value = sbyte1: {0,16}", value.Equals(sbyte1))
      TestObjectForEquality(sbyte1)
      
      Dim ushort1 As UShort = 112
      Console.WriteLine("value = ushort1: {0,16}", value.Equals(ushort1))
      TestObjectForEquality(ushort1)

      Dim uint1 As UInteger = 112
      Console.WriteLine("value = uint1: {0,18}", value.Equals(uint1))
      TestObjectForEquality(uint1)

      Dim ulong1 As ULong = 112
      Console.WriteLine("value = ulong1: {0,17}", value.Equals(ulong1))
      TestObjectForEquality(ulong1)
      
      Dim dec1 As Decimal = 112d
      Console.WriteLine("value = dec1: {0,20}", value.Equals(dec1))
      TestObjectForEquality(dec1)

      Dim dbl1 As Double = 112
      Console.WriteLine("value = dbl1: {0,20}", value.Equals(dbl1))
      TestObjectForEquality(dbl1)
   End Sub
   
   Private Sub TestObjectForEquality(obj As Object)
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj))
      Console.WriteLine()
   End Sub
End Module
' The example displays the following output:
'       value = byte1:             True
'       112 (Single) = 112 (Byte): False
'
'       value = short1:             True
'       112 (Single) = 112 (Int16): False
'
'       value = int1:               True
'       112 (Single) = 112 (Int32): False
'
'       value = long1:              True
'       112 (Single) = 112 (Int64): False
'
'       value = sbyte1:             True
'       112 (Single) = 112 (SByte): False
'
'       value = ushort1:             True
'       112 (Single) = 112 (UInt16): False
'
'       value = uint1:               True
'       112 (Single) = 112 (UInt32): False
'
'       value = ulong1:              True
'       112 (Single) = 112 (UInt64): False
'
'       value = dec1:                 True
'       112 (Single) = 112 (Decimal): False
'
'       value = dbl1:                False
'       112 (Single) = 112 (Double): False

另请参阅

适用于

Equals(Single)

Source:
Single.cs
Source:
Single.cs
Source:
Single.cs

返回一个值，该值指示此实例和指定的 Single 对象是否表示相同的值。

public:
 virtual bool Equals(float obj);
public bool Equals (float obj);
override this.Equals : single -> bool
Public Function Equals (obj As Single) As Boolean

参数

obj
Single

与此实例进行比较的对象。

返回

Boolean

如果 true 与此实例相等，则为 obj；否则为 false。

实现

Equals(T)

注解

有关此 API 的详细信息，请参阅 Single.Equals 的补充 API 说明。

调用方说明

编译器重载解析可能说明两 Equals(Object) 种方法重载的行为存在明显差异。 如果定义了 参数和 之间的Single隐式转换obj，并且参数未类型化为 Object，编译器可能会执行隐式转换并调用 Equals(Single) 方法。 否则，它们会调用 Equals(Object) 方法，如果其obj参数不是Single值，则该方法始终返回 false 。 以下示例演示了两个方法重载之间的行为差异。 对于除 Double Visual Basic 和 C# 中的 和 Double 之外Decimal的所有基元数值类型，第一个比较返回true是因为编译器自动执行扩展转换并调用 Equals(Single) 方法，而第二个比较返回false是因为编译器调用 Equals(Object) 方法。

using System;

public class Example
{
   static float value = 112;
   
   public static void Main()
   {
      byte byte1= 112;
      Console.WriteLine("value = byte1: {0,16}", value.Equals(byte1));
      TestObjectForEquality(byte1);

      short short1 = 112;
      Console.WriteLine("value = short1: {0,16}", value.Equals(short1));
      TestObjectForEquality(short1);

      int int1 = 112;
      Console.WriteLine("value = int1: {0,18}", value.Equals(int1));
      TestObjectForEquality(int1);

      long long1 = 112;
      Console.WriteLine("value = long1: {0,17}", value.Equals(long1));
      TestObjectForEquality(long1);
      
      sbyte sbyte1 = 112;
      Console.WriteLine("value = sbyte1: {0,16}", value.Equals(sbyte1));
      TestObjectForEquality(sbyte1);

      ushort ushort1 = 112;
      Console.WriteLine("value = ushort1: {0,16}", value.Equals(ushort1));
      TestObjectForEquality(ushort1);

      uint uint1 = 112;
      Console.WriteLine("value = uint1: {0,18}", value.Equals(uint1));
      TestObjectForEquality(uint1);

      ulong ulong1 = 112;
      Console.WriteLine("value = ulong1: {0,17}", value.Equals(ulong1));
      TestObjectForEquality(ulong1);
      
      decimal dec1 = 112m;
      Console.WriteLine("value = dec1: {0,21}", value.Equals(dec1));
      TestObjectForEquality(dec1);

      double dbl1 = 112;
      Console.WriteLine("value = dbl1: {0,20}", value.Equals(dbl1));
      TestObjectForEquality(dbl1);
   }

   private static void TestObjectForEquality(Object obj)
   {
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}\n",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj));
   }
}
// The example displays the following output:
//       value = byte1:             True
//       112 (Single) = 112 (Byte): False
//
//       value = short1:             True
//       112 (Single) = 112 (Int16): False
//
//       value = int1:               True
//       112 (Single) = 112 (Int32): False
//
//       value = long1:              True
//       112 (Single) = 112 (Int64): False
//
//       value = sbyte1:             True
//       112 (Single) = 112 (SByte): False
//
//       value = ushort1:             True
//       112 (Single) = 112 (UInt16): False
//
//       value = uint1:               True
//       112 (Single) = 112 (UInt32): False
//
//       value = ulong1:              True
//       112 (Single) = 112 (UInt64): False
//
//       value = dec1:                 False
//       112 (Single) = 112 (Decimal): False
//
//       value = dbl1:                False
//       112 (Single) = 112 (Double): False

let value = 112f

let testObjectForEquality (obj: obj) =
    printfn $"{value} ({value.GetType().Name}) = {obj} ({obj.GetType().Name}): {value.Equals obj}\n"

[<EntryPoint>]
let main _ =
    let byte1= 112uy
    printfn $"value = byte1: {value.Equals byte1,16}"
    testObjectForEquality byte1

    let short1 = 112s
    printfn $"value = short1: {value.Equals short1,16}"
    testObjectForEquality short1

    let int1 = 112
    printfn $"value = int1: {value.Equals int1,18}"
    testObjectForEquality int1

    let long1 = 112L
    printfn $"value = long1: {value.Equals long1,17}"
    testObjectForEquality long1
    
    let sbyte1 = 112y
    printfn $"value = sbyte1: {value.Equals sbyte1,16}"
    testObjectForEquality sbyte1

    let ushort1 = 112us
    printfn $"value = ushort1: {value.Equals ushort1,16}"
    testObjectForEquality ushort1

    let uint1 = 112u
    printfn $"value = uint1: {value.Equals uint1,18}"
    testObjectForEquality uint1

    let ulong1 = 112uL
    printfn $"value = ulong1: {value.Equals ulong1,17}"
    testObjectForEquality ulong1
    
    let dec1 = 112m
    printfn $"value = dec1: {value.Equals dec1,21}"
    testObjectForEquality dec1

    let dbl1 = 112.
    printfn $"value = dbl1: {value.Equals dbl1,20}"
    testObjectForEquality dbl1
    0

// The example displays the following output:
//       value = byte1:             True
//       112 (Single) = 112 (Byte): False
//
//       value = short1:             True
//       112 (Single) = 112 (Int16): False
//
//       value = int1:               True
//       112 (Single) = 112 (Int32): False
//
//       value = long1:              True
//       112 (Single) = 112 (Int64): False
//
//       value = sbyte1:             True
//       112 (Single) = 112 (SByte): False
//
//       value = ushort1:             True
//       112 (Single) = 112 (UInt16): False
//
//       value = uint1:               True
//       112 (Single) = 112 (UInt32): False
//
//       value = ulong1:              True
//       112 (Single) = 112 (UInt64): False
//
//       value = dec1:                 False
//       112 (Single) = 112 (Decimal): False
//
//       value = dbl1:                False
//       112 (Single) = 112 (Double): False

Module Example
   Dim value As Single = 112
   
   Public Sub Main()
      Dim byte1 As Byte = 112
      Console.WriteLine("value = byte1: {0,16}", value.Equals(byte1))
      TestObjectForEquality(byte1)
      
      Dim short1 As Short = 112
      Console.WriteLine("value = short1: {0,16}", value.Equals(short1))
      TestObjectForEquality(short1)

      Dim int1 As Integer = 112
      Console.WriteLine("value = int1: {0,18}", value.Equals(int1))
      TestObjectForEquality(int1)

      Dim long1 As Long = 112
      Console.WriteLine("value = long1: {0,17}", value.Equals(long1))
      TestObjectForEquality(long1)

      Dim sbyte1 As SByte = 112
      Console.WriteLine("value = sbyte1: {0,16}", value.Equals(sbyte1))
      TestObjectForEquality(sbyte1)
      
      Dim ushort1 As UShort = 112
      Console.WriteLine("value = ushort1: {0,16}", value.Equals(ushort1))
      TestObjectForEquality(ushort1)

      Dim uint1 As UInteger = 112
      Console.WriteLine("value = uint1: {0,18}", value.Equals(uint1))
      TestObjectForEquality(uint1)

      Dim ulong1 As ULong = 112
      Console.WriteLine("value = ulong1: {0,17}", value.Equals(ulong1))
      TestObjectForEquality(ulong1)
      
      Dim dec1 As Decimal = 112d
      Console.WriteLine("value = dec1: {0,20}", value.Equals(dec1))
      TestObjectForEquality(dec1)

      Dim dbl1 As Double = 112
      Console.WriteLine("value = dbl1: {0,20}", value.Equals(dbl1))
      TestObjectForEquality(dbl1)
   End Sub
   
   Private Sub TestObjectForEquality(obj As Object)
      Console.WriteLine("{0} ({1}) = {2} ({3}): {4}",
                        value, value.GetType().Name,
                        obj, obj.GetType().Name,
                        value.Equals(obj))
      Console.WriteLine()
   End Sub
End Module
' The example displays the following output:
'       value = byte1:             True
'       112 (Single) = 112 (Byte): False
'
'       value = short1:             True
'       112 (Single) = 112 (Int16): False
'
'       value = int1:               True
'       112 (Single) = 112 (Int32): False
'
'       value = long1:              True
'       112 (Single) = 112 (Int64): False
'
'       value = sbyte1:             True
'       112 (Single) = 112 (SByte): False
'
'       value = ushort1:             True
'       112 (Single) = 112 (UInt16): False
'
'       value = uint1:               True
'       112 (Single) = 112 (UInt32): False
'
'       value = ulong1:              True
'       112 (Single) = 112 (UInt64): False
'
'       value = dec1:                 True
'       112 (Single) = 112 (Decimal): False
'
'       value = dbl1:                False
'       112 (Single) = 112 (Double): False

另请参阅

适用于