Type.Equals 方法

來源:

Type.cs

來源:

Type.cs

來源:

Type.cs

來源:

Type.cs

來源:

Type.cs

public:
 bool Equals(Type ^ o);

public:
 virtual bool Equals(Type ^ o);

public bool Equals(Type o);

public virtual bool Equals(Type? o);

public virtual bool Equals(Type o);

override this.Equals : Type -> bool

Public Function Equals (o As Type) As Boolean

Public Overridable Function Equals (o As Type) As Boolean

參數

傳回

true 若底 o 層系統類型與電流 Type的底層系統類型相同;否則， false。

實作

範例

以下範例用 Equals 來比較兩種類型。

using System;
using System.Reflection;

class Example
{
    public static void Main()
    {

        Type a = typeof(System.String);
        Type b = typeof(System.Int32);

        Console.WriteLine("{0} == {1}: {2}", a, b, a.Equals(b));

        // The Type objects in a and b are not equal,
        // because they represent different types.

        a = typeof(Example);
        b = new Example().GetType();

        Console.WriteLine("{0} is equal to {1}: {2}", a, b, a.Equals(b));

        // The Type objects in a and b are equal,
        // because they both represent type Example.

        b = typeof(Type);

        Console.WriteLine("typeof({0}).Equals(typeof({1})): {2}", a, b, a.Equals(b));

        // The Type objects in a and b are not equal,
        // because variable a represents type Example
        // and variable b represents type Type.

        //Console.ReadLine();
    }
}

//
/* This code example produces the following output:
    System.String == System.Int32: False
    Example is equal to Example: True
    typeof(Example).Equals(typeof(System.Type)): False
*/

open System

type Example() = class end

do
    let a = typeof<string>
    let b = typeof<int>

    printfn $"{a} == {b}: {a.Equals b}"

    // The Type objects in a and b are not equal,
    // because they represent different types.

    let a = typeof<Example>
    let b = Example().GetType()

    printfn $"{a} is equal to {b}: {a.Equals b}"

    // The Type objects in a and b are equal,
    // because they both represent type Example.

    let b = typeof<Type>

    printfn $"typeof({a}).Equals(typeof({b})): {a.Equals b}"

// The Type objects in a and b are not equal,
// because variable a represents type Example
// and variable b represents type Type.

(* This code example produces the following output:
    System.String == System.Int32: False
    Example is equal to Example: True
    typeof(Example).Equals(typeof(System.Type)): False
*)

Imports System.Reflection



Class Example
    
    Public Shared Sub Main() 
        
        Dim a As Type = GetType(System.String)
        Dim b As Type = GetType(System.Int32)
        
        Console.WriteLine("{0} = {1}: {2}", a, b, a.Equals(b))
        ' The Type objects in a and b are not equal,
        ' because they represent different types.

        a = GetType(Example)
        b = New Example().GetType()
        Console.WriteLine("{0} is equal to {1}: {2}", a, b, a.Equals(b))
        ' The Type objects in a and b are equal,
        ' because they both represent type Example.

        b = GetType(Type)
        Console.WriteLine("typeof({0}).Equals(typeof({1})): {2}", a, b, a.Equals(b))
        ' The Type objects in a and b are not equal,
        ' because variable a represents type Example
        ' and variable b represents type Type.

        'Console.ReadLine()
    
    End Sub 
End Class
'
' This code example produces the following output:
'    System.String = System.Int32: False
'    Example is equal to Example: True
'    typeof(Example).Equals(typeof(System.Type)): False
'

另請參閱

• UnderlyingSystemType

來源:

Type.cs

來源:

Type.cs

來源:

Type.cs

來源:

Type.cs

來源:

Type.cs

public:
 override bool Equals(System::Object ^ o);

public override bool Equals(object o);

public override bool Equals(object? o);

override this.Equals : obj -> bool

Public Overrides Function Equals (o As Object) As Boolean

參數

傳回

true 若底 o 層系統類型與電流 Type的底層系統類型相同;否則， false。 此方法若有以下條件也會回傳 false ：

• o 是 null。

• o 無法施放或轉換成 Type 物件。

實作

範例

以下範例用於 Equals(Object) 比較不同 Type 物件實例與不同 Object 實例。

using System;
using System.Collections.Generic;
using System.Reflection;

public class Example
{
   public static void Main()
   {
      Type t =typeof(int);
      Object obj1 = typeof(int).GetTypeInfo();
      IsEqualTo(t, obj1);

      Object obj2 = typeof(String);
      IsEqualTo(t, obj2);
      
      t = typeof(Object);
      Object obj3 = typeof(Object);
      IsEqualTo(t, obj3);
      
      t = typeof(List<>);
      Object obj4 = (new List<String>()).GetType();
      IsEqualTo(t, obj4);
      
      t = typeof(Type);
      Object obj5 = null;
      IsEqualTo(t, obj5);
   }
   
   private static void IsEqualTo(Type t, Object inst)
   {
      Type t2 = inst as Type;
      if (t2 != null)
         Console.WriteLine("{0} = {1}: {2}", t.Name, t2.Name,
                           t.Equals(t2));
      else
         Console.WriteLine("Cannot cast the argument to a type.");

      Console.WriteLine();                        
   }
}
// The example displays the following output:
//       Int32 = Int32: True
//       
//       Int32 = String: False
//       
//       Object = Object: True
//       
//       List`1 = List`1: False
//       
//       Cannot cast the argument to a type.

open System
open System.Reflection

let isEqualTo (t: Type) (inst: obj) =
    match inst with
    | :? Type as t2 ->
        printfn $"{t.Name} = {t2.Name}: {t.Equals t2}\n"
    | _ ->
        printfn "Cannot cast the argument to a type.\n"

do 
    let t = typeof<int>
    typeof<int>.GetTypeInfo()
    |> isEqualTo t

    typeof<String>
    |> isEqualTo t

    let t = typeof<obj>
    typeof<obj>
    |> isEqualTo t

    let t = typeof<ResizeArray<_>>.GetGenericTypeDefinition()
    let obj4: obj = (ResizeArray<String>()).GetType()
    isEqualTo t obj4

    let t = typeof<Type>
    let obj5: obj = null
    isEqualTo t obj5
// The example displays the following output:
//       Int32 = Int32: True
//       
//       Int32 = String: False
//       
//       Object = Object: True
//       
//       List`1 = List`1: False
//       
//       Cannot cast the argument to a type.

Imports System.Collections.Generic
Imports System.Reflection

Module Example
   Public Sub Main()
      Dim t As Type = GetType(Integer)
      Dim obj1 As Object = GetType(Integer).GetTypeInfo()
      IsEqualTo(t, obj1)

      Dim obj2 As Object = GetType(String)
      IsEqualTo(t, obj2)
      
      t = GetType(Object)
      Dim obj3 As Object = GetType(Object)
      IsEqualTo(t, obj3)
      
      t = GetType(List(Of ))
      Dim obj4 As Object = (New List(Of String())).GetType()
      IsEqualTo(t, obj4)
      
      t = GetType(Type)
      Dim obj5 As Object = Nothing
      IsEqualTo(t, obj5)
   End Sub
   
   Private Sub IsEqualTo(t As Type, inst As Object)
      Dim t2 As Type = TryCast(inst, Type)
      If t2 IsNot Nothing Then
         Console.WriteLine("{0} = {1}: {2}", t.Name, t2.Name,
                           t.Equals(t2))
      Else
         Console.WriteLine("Cannot cast the argument to a type.")
      End If
      Console.WriteLine()                        
   End Sub
End Module
' The example displays the following output:
'       Int32 = Int32: True
'       
'       Int32 = String: False
'       
'       Object = Object: True
'       
'       List`1 = List`1: False
'       
'       Cannot cast the argument to a type.

關於這個例子，有兩點特別值得注意：

• Type將代表整數的物件與TypeInfo表示整數返回true的物件比較，因為 TypeInfo 是從 推導出來Type的。

• 將代表Type物件（開放泛型）與IList<T>物件（閉泛型）比較List(Of String)時，會返回 false。

備註

這個方法會覆寫 Object.Equals。 它會將 o 投射到 的 Type 物件並呼叫該 Type.Equals(Type) 方法。

另請參閱

• UnderlyingSystemType