C#学习笔记之——接口实例

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using System;namespace test_2_1{    interface IDimensions  //声明接口IDimensions    {        float getLength();  //包含的方法1        float getWidth();   //包含的方法2    }    class Box : IDimensions   //声明类Box继承于接口IDimensions    {        float lengthInches;        float widthInches;        Box(float length, float width)            {            lengthInches = length;            widthInches = width;        }        // Explicit interface member implementation:         float IDimensions.getLength()    //该类显式实现接口成员 getLength 和 getWidth        {            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());  //错误的原因是不能直接实例化接口            //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());            Console.WriteLine("Press any key to exit.");            Console.ReadKey();        }    }}

显式接口实现还允许程序员实现具有相同成员名称的两个接口，并为每个接口成员各提供一个实现。本示例同时以公制单位和英制单位显示框的尺寸。Box 类实现 IEnglishDimensions 和 IMetricDimensions 两个接口，它们表示不同的度量系统。两个接口有相同的成员名称 Length 和 Width。

using System;namespace test_2_2{    // Declare the English units interface:    interface IEnglishDimensions    {        float Length();        float Width();    }    // Declare the metric units interface:    interface IMetricDimensions    {        float Length();        float Width();    }    // Declare the Box class that implements the two interfaces:    // IEnglishDimensions and IMetricDimensions:    class Box : IEnglishDimensions, IMetricDimensions    {        float lengthInches;        float widthInches;        public Box(float length, float width)        {            lengthInches = length;            widthInches = width;        }        // Explicitly implement the members of IEnglishDimensions:        float IEnglishDimensions.Length()        {            return lengthInches;        }        float IEnglishDimensions.Width()        {            return widthInches;        }        // Explicitly implement the members of IMetricDimensions:        float IMetricDimensions.Length()        {            return lengthInches * 2.54f;        }        float IMetricDimensions.Width()        {            return widthInches * 2.54f;        }        static void Main()        {            // Declare a class instance box1:            Box box1 = new Box(30.0f, 20.0f);            // Declare an instance of the English units interface:            IEnglishDimensions eDimensions = (IEnglishDimensions)box1;            // Declare an instance of the metric units interface:            IMetricDimensions mDimensions = (IMetricDimensions)box1;            // Print dimensions in English units:            System.Console.WriteLine("Length(in): {0}", eDimensions.Length());            System.Console.WriteLine("Width (in): {0}", eDimensions.Width());            // Print dimensions in metric units:            System.Console.WriteLine("Length(cm): {0}", mDimensions.Length());            System.Console.WriteLine("Width (cm): {0}", mDimensions.Width());            Console.WriteLine("Press any key to exit.");            Console.ReadKey();        }    }}

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