C＃| Type.HasElementTypeImpl()方法

Type.HasElementTypeImpl()方法在派生类中重写时使用，实现HasElementType属性并确定当前Type是否包含或引用另一种类型。这意味着此方法检查当前Type是数组，指针还是通过引用传递。

Syntax: protected abstract bool HasElementTypeImpl ();

Return Value: This method returns true if the Type is an array, a pointer, or is passed by reference otherwise, false.

下面的程序说明了Type.HasElementTypeImpl()方法的用法：

范例1：

// C# program to demonstrate the
// Type.HasElementTypeImpl() Method
using System;
using System.Globalization;
using System.Reflection;
  
class GFG {
  
    // Main Method
    public static void Main()
    {
        // creating and initializing object of MyClass
        MyClass mytype = new MyClass(typeof(int));
  
        // checking if mytype has any elementtype or not
        if (mytype.HasElementType)
            Console.WriteLine("The type of myArray is {0}.", mytype.elementtype);
        else
            Console.WriteLine("myArray is not an array, pointer, or reference type.");
    }
}
  
// Defining MyClass extended from TypeDelegator
public class MyClass : TypeDelegator {
  
    // creating and initializing elementtype with null
    public string elementtype = null;
  
    // creating and initializing type with null
    private Type type = null;
  
    // Constructor
    public MyClass(Type type)
                 : base(type)
    {
        this.type = type;
    }
  
    // Override Type.HasElementTypeImpl().
    protected override bool HasElementTypeImpl()
    {
  
        // Determine whether the type is an array.
        if (type.IsArray) {
            elementtype = "array";
            return true;
        }
  
        // Determine whether the type is a reference.
        if (type.IsByRef) 
        {
            elementtype = "reference";
            return true;
        }
  
        // Determine whether the type is a pointer.
        if (type.IsPointer)
        {
            elementtype = "pointer";
            return true;
        }
  
        // Return false if the type is not
        // a reference, array, or pointer type.
        return false;
    }
}

输出：

myArray is not an array, pointer, or reference type.

范例2：

// C# program to demonstrate the
// Type.HasElementTypeImpl() Method
using System;
using System.Globalization;
using System.Reflection;
  
class GFG {
  
    // Main Method
    public static void Main()
    {
        // creating and initializing object of MyClass
        MyClass mytype = new MyClass(typeof(int[,,,,,, ]));
  
        // checking if mytype has any elementtype or not
        if (mytype.HasElementType)
            Console.WriteLine("The type of {1} is {0}.",
                       mytype.elementtype, mytype.type);
        else
            Console.WriteLine("{0} is not an array, pointer, or reference type.",
                                                                    mytype.type);
    }
}
  
// Defining MyClass extended from TypeDelegator
public class MyClass : TypeDelegator {
  
    // creating and initializing elementtype with null
    public string elementtype = null;
  
    // creating and initializing type with null
    public Type type = null;
  
    // Constructor
    public MyClass(Type type)
                : base(type)
    {
        this.type = type;
    }
  
    // Override Type.HasElementTypeImpl().
    protected override bool HasElementTypeImpl()
    {
        // Determine whether the type is an array.
        if (type.IsArray) 
        {
  
            elementtype = "array";
            return true;
        }
  
        // Determine whether the type is a reference.
        if (type.IsByRef) 
        {
            elementtype = "reference";
            return true;
        }
  
        // Determine whether the type is a pointer.
        if (type.IsPointer) 
        {
            elementtype = "pointer";
            return true;
        }
  
        // Return false if the type is not a 
        // reference, array, or a pointer type
        return false;
    }
}

输出：

The type of System.Int32[,,,,,,] is array.

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.type.haselementtypeimpl?view=netframework-4.8