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📜  C＃访问修饰符

📅  最后修改于: 2020-10-31 03:13:35             🧑  作者: Mango

C＃访问修饰符/说明符

C＃访问修饰符或说明符是用于指定C＃应用程序中变量和函数的可访问性或范围的关键字。

C＃提供了五种类型的访问说明符。

  • 上市
  • 受保护的
  • 内部
  • 内部保护
  • 私人的

我们可以选择任何一种来保护我们的数据。公共不受限制，私人受最大限制。下表介绍了每种服务器的可访问性。

Access Specifier Description
Public It specifies that access is not restricted.
Protected It specifies that access is limited to the containing class or in derived class.
Internal It specifies that access is limited to the current assembly.
protected internal It specifies that access is limited to the current assembly or types derived from the containing class.
Private It specifies that access is limited to the containing type.

现在，让我们创建示例来检查每个访问说明符的可访问性。

1)C＃公共访问说明符

它使数据可以公开访问。它不会将数据限制为已声明的块。

例

using System;
namespace AccessSpecifiers
{
    class PublicTest
    {
        public string name = "Shantosh Kumar";
        public void Msg(string msg)
        {
            Console.WriteLine("Hello " + msg);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            PublicTest publicTest = new PublicTest();
            // Accessing public variable
            Console.WriteLine("Hello " + publicTest.name);
            // Accessing public function
            publicTest.Msg("Peter Decosta");
        }
    }
}

输出：

Hello Shantosh Kumar
Hello Peter Decosta

2)C＃受保护的访问说明符

它可以在该类中访问，并且作用域有限。在继承的情况下，也可以在子类或子类中访问它。

例

using System;
namespace AccessSpecifiers
{
    class ProtectedTest
    {
        protected string name = "Shashikant";
        protected void Msg(string msg)
        {
            Console.WriteLine("Hello " + msg);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            ProtectedTest protectedTest = new ProtectedTest();
            // Accessing protected variable
            Console.WriteLine("Hello "+ protectedTest.name);
            // Accessing protected function
            protectedTest.Msg("Swami Ayyer");
        }
    }
}

输出：

Compile time error
'ProtectedTest.name' is inaccessible due to its protection level.

例2

在这里，我们通过继承访问子类中受保护的成员。

using System;
namespace AccessSpecifiers
{
    class ProtectedTest
    {
        protected string name = "Shashikant";
        protected void Msg(string msg)
        {
            Console.WriteLine("Hello " + msg);
        }
    }
    class Program : ProtectedTest
    {
        static void Main(string[] args)
        {
            Program program = new Program();
            // Accessing protected variable
            Console.WriteLine("Hello " + program.name);
            // Accessing protected function
            program.Msg("Swami Ayyer");
        }
    }    
}

输出：

Hello Shashikant
Hello Swami Ayyer

3)C＃内部访问说明符

internal关键字用于为变量和函数指定内部访问说明符。该说明符只能在同一程序集中的文件中访问。

例

using System;
namespace AccessSpecifiers
{
    class InternalTest
    {
        internal string name = "Shantosh Kumar";
        internal void Msg(string msg)
        {
            Console.WriteLine("Hello " + msg);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            InternalTest internalTest = new InternalTest();
            // Accessing internal variable
            Console.WriteLine("Hello " + internalTest.name);
            // Accessing internal function
            internalTest.Msg("Peter Decosta");
        }
    }
}

输出：

Hello Shantosh Kumar
Hello Peter Decosta

4)受C＃保护的内部访问说明符

声明为protected internal的变量或函数可以在声明了该变量或函数的程序集中进行访问。也可以在另一个程序集中的派生类中访问它。

例

using System;
namespace AccessSpecifiers
{
    class InternalTest
    {
        protected internal string name = "Shantosh Kumar";
        protected internal void Msg(string msg)
        {
            Console.WriteLine("Hello " + msg);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            InternalTest internalTest = new InternalTest();
            // Accessing protected internal variable
            Console.WriteLine("Hello " + internalTest.name);
            // Accessing protected internal function
            internalTest.Msg("Peter Decosta");
        }
    }
}

输出：

Hello Shantosh Kumar
Hello Peter Decosta

5)C＃专用访问说明符

私有访问说明符用于指定对变量或函数的私有可访问性。它是限制性最强的，并且只能在声明它的类的主体内访问。

例

using System;
namespace AccessSpecifiers
{
    class PrivateTest
    {
        private string name = "Shantosh Kumar";
        private void Msg(string msg)
        {
            Console.WriteLine("Hello " + msg);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            PrivateTest privateTest = new PrivateTest();
            // Accessing private variable
            Console.WriteLine("Hello " + privateTest.name);
            // Accessing private function
            privateTest.Msg("Peter Decosta");
        }
    }
}

输出：

Compile time error
'PrivateTest.name' is inaccessible due to its protection level.

C＃专用说明符示例2

using System;
namespace AccessSpecifiers
{
    class Program
    {
        private string name = "Shantosh Kumar";
        private void Msg(string msg)
        {
            Console.WriteLine("Hello " + msg);
        }
        static void Main(string[] args)
        {
            Program program = new Program();
            // Accessing private variable
            Console.WriteLine("Hello " + program.name);
            // Accessing private function
            program.Msg("Peter Decosta");
        }
    }
}

输出：

Hello Shantosh Kumar
Hello Peter Decosta