Type.IsAssignableFrom メソッド
指定した Type のインスタンスを現在の Type のインスタンスに代入できるかどうかを判断します。
Public Overridable Function IsAssignableFrom( _
ByVal c As Type _) As Boolean
[C#]
public virtual bool IsAssignableFrom(Typec);
[C++]
public: virtual bool IsAssignableFrom(Type* c);
[JScript]
public function IsAssignableFrom(
c : Type) : Boolean;
パラメータ
- c
現在の Type と比較する Type。
戻り値
c パラメータと現在の Type が同じ型を表している場合、現在の Type が c の継承階層にある場合、または現在の Type が c によってサポートされるインターフェイスである場合は true 。これらの条件のいずれも該当しない場合、または c が null 参照 (Visual Basic では Nothing) である場合は false 。
解説
このメソッドは、派生クラスでオーバーライドできます。
GetElementType を使用して、Type の要素型を判別します。
使用例
[Visual Basic, C#, C++] 配列を使用する IsAssignable メソッドの例を次に示します。
Imports System
Class ArrayTypeTest
Public Shared Sub Main()
Dim i As Integer = 1
Dim array10(10) As Integer
Dim array2(2) As Integer
Dim array22(2, 2) As Integer
Dim array24(2, 4) As Integer
Dim array333(3, 3, 3) As Integer
Dim array10Type As Type = array10.GetType()
Dim array2Type As Type = array2.GetType()
Dim array22Type As Type = array22.GetType()
Dim array24Type As Type = array24.GetType()
Dim array333Type As Type = array333.GetType()
' If X and Y are not both arrays, then return false.
Console.WriteLine("Is int[2] assignable from int? {0}.", array2Type.IsAssignableFrom(i.GetType()))
' If X and Y have same type and rank, then return true.
Console.WriteLine("Is int[2] assignable from int[10]? {0}.", array2Type.IsAssignableFrom(array10Type))
Console.WriteLine("Is int[2,2] assignable from int[2,4]? {0}.", array22Type.IsAssignableFrom(array24Type))
Console.WriteLine("Is int[2,4] assignable from int[2,2]? {0}.", array24Type.IsAssignableFrom(array22Type))
' If X and Y do not have the same rank, then return false.
Console.WriteLine("Is int[2,2] assignable from int[10]? {0}.", array22Type.IsAssignableFrom(array10Type))
Console.WriteLine("Is int[2,2] assignable from int[3,3,3]? {0}.", array22Type.IsAssignableFrom(array333Type))
Console.WriteLine("Is int[3,3,3] is assignable from int[2,2]? {0}.", array333Type.IsAssignableFrom(array22Type))
End Sub 'Main
End Class 'ArrayTypeTest
[C#]
using System;
class ArrayTypeTest
{
public static void Main()
{
int i = 1;
int [] array10 = new int [10];
int [] array2 = new int[2];
int [,]array22 = new int[2,2];
int [,]array24 = new int[2,4];
int [,,]array333 = new int[3,3,3];
Type array10Type = array10.GetType();
Type array2Type = array2.GetType();
Type array22Type = array22.GetType();
Type array24Type = array24.GetType();
Type array333Type = array333.GetType();
// If X and Y are not both arrays, then return false.
Console.WriteLine("Is int[2] assignable from int? {0}.", array2Type.IsAssignableFrom(i.GetType()));
// If X and Y have same type and rank, then return true.
Console.WriteLine("Is int[2] assignable from int[10]? {0}.", array2Type.IsAssignableFrom(array10Type));
Console.WriteLine("Is int[2,2] assignable from int[2,4]? {0}.", array22Type.IsAssignableFrom(array24Type));
Console.WriteLine("Is int[2,4] assignable from int[2,2]? {0}.", array24Type.IsAssignableFrom(array22Type));
// If X and Y do not have the same rank, then return false.
Console.WriteLine("Is int[2,2] assignable from int[10]? {0}.", array22Type.IsAssignableFrom(array10Type));
Console.WriteLine("Is int[2,2] assignable from int[3,3,3]? {0}.", array22Type.IsAssignableFrom(array333Type));
Console.WriteLine("Is int[3,3,3] assignable from int[2,2]? {0}.", array333Type.IsAssignableFrom(array22Type));
}
}
[C++]
#using <mscorlib.dll>
using namespace System;
int main() {
Int32 i = 1;
Int32 array10[] = new Int32[10];
Int32 array2[] = new Int32[2];
Int32 array22[,] = new Int32[2, 2];
Int32 array24[,] = new Int32[2, 4];
Int32 array333[,,] = new Int32[3, 3, 3];
Type* array10Type = array10->GetType();
Type* array2Type = array2->GetType();
Type* array22Type = array22->GetType();
Type* array24Type = array24->GetType();
Type* array333Type = array333->GetType();
// If X and Y are not both arrays, then return false.
Console::WriteLine(S"Is Int32[2] assignable from Int32? {0}.", array2Type->IsAssignableFrom(__box(i)->GetType()).ToString());
// If X and Y have same type and rank, then return true.
Console::WriteLine(S"Is Int32[2] assignable from Int32[10]? {0}.", array2Type->IsAssignableFrom(array10Type).ToString());
Console::WriteLine(S"Is Int32[2,2] assignable from Int32[2,4]? {0}.", array22Type->IsAssignableFrom(array24Type).ToString());
Console::WriteLine(S"Is Int32[2,4] assignable from Int32[2,2]? {0}.", array24Type->IsAssignableFrom(array22Type).ToString());
// If X and Y do not have the same rank, then return false.
Console::WriteLine(S"Is Int32[2,2] assignable from Int32[10]? {0}.", array22Type->IsAssignableFrom(array10Type).ToString());
Console::WriteLine(S"Is Int32[2,2] assignable from Int32[3,3,3]? {0}.", array22Type->IsAssignableFrom(array333Type).ToString());
Console::WriteLine(S"Is Int32[3,3,3] assignable from int[2,2]? {0}.", array333Type->IsAssignableFrom(array22Type).ToString());
}
[Visual Basic, C#, C++] このコードによって、次の出力が生成されます。
int[2] is assignable from int? False
int[2] is assignable from int[10]? True
int[2,2] is assignable from int[2,4]? True
int[2,4] is assignable from int[2,2]? True
int[2,2] is assignable from int[10]? False
int[2,2] is assignable from int[3,3,3]? False
int[3,3,3] is assignable from int[2,2]? False
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必要条件
プラットフォーム: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 ファミリ, .NET Compact Framework - Windows CE .NET, Common Language Infrastructure (CLI) Standard