C# Type.IsEnumDefined()用法及代碼示例

Type.IsEnumDefined(Object)方法用於返回一個值，該值指示當前枚舉類型中是否存在指定的值。

用法： public virtual bool IsEnumDefined (object value);

Here, it takes the value to be tested.

返回值：如果指定的值是當前枚舉類型的成員，則此方法返回true，否則返回false。

異常：

ArgumentException：如果當前類型不是枚舉。
ArgumentNullException：如果值為null。
InvalidOperationException：如果值的類型不能為枚舉的基礎類型。

以下示例程序旨在說明Type.IsEnumDefined(Object)方法的用法：

示例1:

// C# program to demonstrate the 
// Type.IsEnumDefined(Object) Method 
using System; 
using System.Globalization; 
using System.Reflection; 
  
class GFG { 
  
    // defining enum enu 
    public enum enu {A, B, C}; 
  
    // Main Method 
    public static void Main() 
    { 
  
        // try-catch block for handling Exception 
        try { 
  
            // creating and initializing object Type 
            object value = enu.A; 
  
            // checking for the current enumeration type 
            // by using IsEnumDefined() Method 
            bool status = typeof(enu).IsEnumDefined(value); 
  
            // display the result 
            if (status) 
                Console.WriteLine("specified value is a member"+ 
                            " of the current enumeration type"); 
            else
                Console.WriteLine("specified value is not"+ 
                " present in the current enumeration type"); 
        } 
  
        // catch ArgumentNullException here 
        catch (ArgumentNullException e) { 
  
            Console.WriteLine("Object is null."); 
            Console.Write("Exception Thrown: "); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
  
        // catch ArgumentNullException here 
        catch (InvalidOperationException e) { 
  
            Console.WriteLine("Object is null."); 
            Console.Write("Exception Thrown: "); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
  
        // catch ArgumentException here 
        catch (ArgumentException e) { 
  
            Console.WriteLine("Object is null."); 
            Console.Write("Exception Thrown: "); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
    } 
}

輸出：

specified value is a member of the current enumeration type

示例2:

// C# program to demonstrate the 
// Type.IsEnumDefined(Object) Method 
using System; 
using System.Globalization; 
using System.Reflection; 
  
class GFG { 
  
    // defining enum enu 
    public enum enu {A, B, C}; 
  
    // Main Method 
    public static void Main() 
    { 
  
        // try-catch block for handling Exception 
        try { 
  
            // creating and initializing object Type 
            object value = enu.B; 
  
            // checking for the current enumeration type 
            // by using IsEnumDefined() Method 
            bool status = typeof(int).IsEnumDefined(value); 
  
            // display the result 
            if (status) 
                Console.WriteLine("specified value is a member"+ 
                            " of the current enumeration type"); 
            else
                Console.WriteLine("specified value is not"+ 
               " present in the current enumeration type"); 
        } 
  
        // catch ArgumentNullException here 
        catch (ArgumentNullException e) { 
  
            Console.WriteLine("value is null."); 
            Console.Write("Exception Thrown: "); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
  
        // catch ArgumentException here 
        catch (ArgumentException e) { 
  
            Console.WriteLine("The current type is not an enumeration."); 
            Console.Write("Exception Thrown: "); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
    } 
}

輸出：

The current type is not an enumeration.
Exception Thrown: System.ArgumentException

示例3:

// C# program to demonstrate the 
// Type.IsEnumDefined(Object) Method 
using System; 
using System.Globalization; 
using System.Reflection; 
  
class GFG { 
  
    // defining enum enu 
    public enum enu {A, B, C}; 
  
    // Main Method 
    public static void Main() 
    { 
  
        // try-catch block for handling Exception 
        try { 
  
            // creating and initializing object Type 
            object value = null; 
  
            // checking for the current enumeration type 
            // by using IsEnumDefined() Method 
            bool status = typeof(enu).IsEnumDefined(value); 
  
            // display the result 
            if (status) 
                Console.WriteLine("specified value is a member"+ 
                            " of the current enumeration type"); 
            else
                Console.WriteLine("specified value is not"+  
                " present in the current enumeration type"); 
        } 
  
        // catch ArgumentNullException here 
        catch (ArgumentNullException e) { 
  
            Console.WriteLine("value is null."); 
            Console.Write("Exception Thrown: "); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
  
        // catch ArgumentException here 
        catch (ArgumentException e) { 
  
            Console.WriteLine("The current type is not an enumeration."); 
            Console.Write("Exception Thrown: "); 
            Console.Write("{0}", e.GetType(), e.Message); 
        } 
    } 
}

輸出：

value is null.
Exception Thrown: System.ArgumentNullException

參考：

https://docs.microsoft.com/en-us/dotnet/api/system.type.isenumdefined?view=netframework-4.8

相關用法

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