如何：显式实现接口成员（C# 编程指南） · MSDN C# 编程指南 & 参考手册 2015

# 如何：显式实现接口成员（C# 编程指南）本示例声明一个 [接口](https://msdn.microsoft.com/zh-CN/library/87d83y5b.aspx)IDimensions 和一个类 Box，该类显式实现接口成员 getLength 和 getWidth。通过接口实例 dimensions 访问这些成员。 ``` interface IDimensions { float getLength(); float getWidth(); } class Box : IDimensions { float lengthInches; float widthInches; Box(float length, float width) { lengthInches = length; widthInches = width; } // Explicit interface member implementation: float IDimensions.getLength() { return lengthInches; } // Explicit interface member implementation: float IDimensions.getWidth() { return widthInches; } static void Main() { // Declare a class instance box1: Box box1 = new Box(30.0f, 20.0f); // Declare an interface instance dimensions: IDimensions dimensions = (IDimensions)box1; // The following commented lines would produce compilation // errors because they try to access an explicitly implemented // interface member from a class instance: //System.Console.WriteLine("Length: {0}", box1.getLength()); //System.Console.WriteLine("Width: {0}", box1.getWidth()); // Print out the dimensions of the box by calling the methods // from an instance of the interface: System.Console.WriteLine("Length: {0}", dimensions.getLength()); System.Console.WriteLine("Width: {0}", dimensions.getWidth()); } } /* Output: Length: 30 Width: 20 */ ``` ## 可靠编程 * 请注意 **Main** 方法中下列代码行被注释掉，因为它们将产生编译错误。显式实现的接口成员不能从[类](https://msdn.microsoft.com/zh-CN/library/0b0thckt.aspx)实例访问： ``` //System.Console.WriteLine("Length: {0}", box1.getLength()); //System.Console.WriteLine("Width: {0}", box1.getWidth()); ``` * 还请注意，**Main** 方法中的下列代码行成功输出框的尺寸，因为这些方法是从接口实例调用的： ``` System.Console.WriteLine("Length: {0}", dimensions.getLength()); System.Console.WriteLine("Width: {0}", dimensions.getWidth()); ``` ## 请参阅 [C# 编程指南](https://msdn.microsoft.com/zh-CN/library/67ef8sbd.aspx) [类和结构（C# 编程指南）](https://msdn.microsoft.com/zh-CN/library/ms173109.aspx) [接口（C# 编程指南）](https://msdn.microsoft.com/zh-CN/library/ms173156.aspx) [如何：显式实现两个接口的成员（C# 编程指南）](https://msdn.microsoft.com/zh-CN/library/4taxa8t2.aspx)