Nullable<T>.Equals(Object) 方法
定义
重要
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指示当前 Nullable<T> 对象是否等于指定对象。
public:
override bool Equals(System::Object ^ other);public override bool Equals(object other);public override bool Equals(object? other);override this.Equals : obj -> boolPublic Overrides Function Equals (other As Object) As Boolean参数
- other
- Object
对象。
返回
下表介绍了如何为比较值定义相等性：
| 返回值 | 说明 |
|---|---|
true | 该HasValue属性是false，并且other参数是null（即，两个 null 值按定义相等），或者HasValue该属性返回trueValue的值等于other参数。
|
false | 当前HasValueNullable<T>结构的属性为，参数other为truenull，或HasValue当前Nullable<T>结构的属性为falseother，参数不null为，或HasValue当前Nullable<T>结构的属性为true，属性返回Value的值不等于other参数。
|
示例
下面的代码示例确定对象和 Nullable<T> 对象是否等于当前 Nullable<T> 对象。
// This code example demonstrates the Nullable<T>.Equals
// methods.
using System;
class Sample
{
public static void Main()
{
int? nullInt1 = 100;
int? nullInt2 = 200;
object myObj;
// Determine if two nullable of System.Int32 values are equal.
// The nullable objects have different values.
Console.Write("1) nullInt1 and nullInt2 ");
if (nullInt1.Equals(nullInt2))
Console.Write("are");
else
Console.Write("are not");
Console.WriteLine(" equal.");
// Determine if a nullable of System.Int32 and an object
// are equal. The object contains the boxed value of the
// nullable object.
myObj = (object)nullInt1;
Console.Write("2) nullInt1 and myObj ");
if (nullInt1.Equals(myObj))
Console.Write("are");
else
Console.Write("are not");
Console.WriteLine(" equal.");
}
}
/*
This code example produces the following results:
1) nullInt1 and nullInt2 are not equal.
2) nullInt1 and myObj are equal.
*/
// This code example demonstrates the Nullable<T>.Equals
// methods.
open System
let nullInt1 = Nullable 100
let nullInt2 = Nullable 200
// Determine if two nullable of System.Int32 values are equal.
// The nullable objects have different values.
printf "1) nullInt1 and nullInt2 "
if nullInt1.Equals nullInt1 then
printf "are"
else
printf "are not"
printfn " equal."
// Determine if a nullable of System.Int32 and an object
// are equal. The object contains the boxed value of the
// nullable object.
let myObj = box nullInt1
printf "2) nullInt1 and myObj "
if nullInt1.Equals myObj then
printf "are"
else
printf "are not"
printfn " equal."
// This code example produces the following results:
// 1) nullInt1 and nullInt2 are not equal.
// 2) nullInt1 and myObj are equal.
' This code example demonstrates the Nullable(Of T).Equals
' methods.
Class Sample
Public Shared Sub Main()
Dim nullInt1 As Nullable(Of Integer) = 100
Dim nullInt2 As Nullable(Of Integer) = 200
Dim myObj As Object
' Determine if two nullable of System.Int32 values are equal.
' The nullable objects have different values.
Console.Write("1) nullInt1 and nullInt2 ")
If nullInt1.Equals(nullInt2) Then
Console.Write("are")
Else
Console.Write("are not")
End If
Console.WriteLine(" equal.")
' Determine if a nullable of System.Int32 and an object
' are equal. The object contains the boxed value of the
' nullable object.
myObj = CType(nullInt1, Object)
Console.Write("2) nullInt1 and myObj ")
If nullInt1.Equals(myObj) Then
Console.Write("are")
Else
Console.Write("are not")
End If
Console.WriteLine(" equal.")
End Sub
End Class
'
'This code example produces the following results:
'
'1) nullInt1 and nullInt2 are not equal.
'2) nullInt1 and myObj are equal.
'
注解
HasValue如果当前Nullable<T>结构的属性不true为参数othernull，则通过将other参数传递给Equals当前Nullable<T>结构的基础值的方法来确定相等性。
