现在的位置: 首页 > 综合 > 正文

C#基础概念二十五问

2013年09月03日 ⁄ 综合 ⁄ 共 18578字 ⁄ 字号 评论关闭
示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example01
{
    class Program
    {
        class Class1
        {
            public static String staticStr = "Class";
            public String notstaticStr = "Obj";
        }
        static void Main(string[] args)
        {
            //静态变量通过类进行访问,该类所有实例的同一静态变量都是同一个值
            Console.WriteLine("Class1's staticStr: {0}", Class1.staticStr);
 
            Class1 tmpObj1 = new Class1();
            tmpObj1.notstaticStr = "tmpObj1";
            Class1 tmpObj2 = new Class1();
            tmpObj2.notstaticStr = "tmpObj2";
 
            //非静态变量通过对象进行访问,不同对象的同一非静态变量可以有不同的值
            Console.WriteLine("tmpObj1's notstaticStr: {0}", tmpObj1.notstaticStr);
            Console.WriteLine("tmpObj2's notstaticStr: {0}", tmpObj2.notstaticStr);
 
            Console.ReadLine();
        }
    }
}
结果:
Class1's staticStr: Class
tmpObj1's notstaticStr: tmpObj1
tmpObj2's notstaticStr: tmpObj2

示例:
测试类:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example02Lib
{
    public class Class1
    {
        public const String strConst = "Const";
        public static readonly String strStaticReadonly = "StaticReadonly";
        //public const String strConst = "Const Changed";
        //public static readonly String strStaticReadonly = "StaticReadonly Changed";
    }
}
 
客户端代码:
using System;
using System.Collections.Generic;
using System.Text;
using Example02Lib;
 
namespace Example02
{
    class Program
    {
        static void Main(string[] args)
        {
            //修改Example02中Class1的strConst初始值后,只编译Example02Lib项目
            //然后到资源管理器里把新编译的Example02Lib.dll拷贝Example02.exe所在的目录,执行Example02.exe
            //切不可在IDE里直接调试运行因为这会重新编译整个解决方案!!
 
            //可以看到strConst的输出没有改变,而strStaticReadonly的输出已经改变
            //表明Const变量是在编译期初始化并嵌入到客户端程序,而StaticReadonly是在运行时初始化的
            Console.WriteLine("strConst : {0}", Class1.strConst);
            Console.WriteLine("strStaticReadonly : {0}", Class1.strStaticReadonly);
 
            Console.ReadLine();
        }
    }
}
结果:
strConst : Const
strStaticReadonly : StaticReadonly
修改后的示例:
测试类:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example02Lib
{
    public class Class1
    {
        //public const String strConst = "Const";
        //public static readonly String strStaticReadonly = "StaticReadonly";
        public const String strConst = "Const Changed";
        public static readonly String strStaticReadonly = "StaticReadonly Changed";
    }
}
结果
strConst : Const
strStaticReadonly : StaticReadonly Changed

示例:
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
 
namespace Example03
{
    class Program
    {
        //注意DllImport是一个Attribute Property,在System.Runtime.InteropServices命名空间中定义
        //extern与DllImport一起使用时必须再加上一个static修饰符
        [DllImport("User32.dll")]
        public static extern int MessageBox(int Handle, string Message, string Caption, int Type);
 
        static int Main()
        {
            string myString;
            Console.Write("Enter your message: ");
            myString = Console.ReadLine();
            return MessageBox(0, myString, "My Message Box", 0);
        }
    }
}
结果:

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example04
{
    #region 基类,抽象类
    public abstract class BaseClass
    {
        //抽象属性,同时具有get和set访问器表示继承类必须将该属性实现为可读写
        public abstract String Attribute
        {
            get;
            set;
        }
 
        //抽象方法,传入一个字符串参数无返回值
        public abstract void Function(String value);
 
        //抽象事件,类型为系统预定义的代理(delegate):EventHandler
        public abstract event EventHandler Event;
 
        //抽象索引指示器,只具有get访问器表示继承类必须将该索引指示器实现为只读
        public abstract Char this[int Index]
        {
            get;
        }
    }
    #endregion
 
    #region 继承类
    public class DeriveClass : BaseClass
    {
        private String attribute;
 
        public override String Attribute
        {
            get
            {
                return attribute;
            }
            set
            {
                attribute = value;
            }
        }
        public override void Function(String value)
        {
            attribute = value;
            if (Event != null)
            {
                Event(this, new EventArgs());
            }
        }
        public override event EventHandler Event;
        public override Char this[int Index]
        {
            get
            {
                return attribute[Index];
            }
        }
    }
    #endregion
 
    class Program
    {
        static void OnFunction(object sender, EventArgs e)
        {
            for (int i = 0; i < ((DeriveClass)sender).Attribute.Length; i++)
            {
                Console.WriteLine(((DeriveClass)sender)[i]);
            }
        }
        static void Main(string[] args)
        {
            DeriveClass tmpObj = new DeriveClass();
 
            tmpObj.Attribute = "1234567";
            Console.WriteLine(tmpObj.Attribute);
 
            //将静态函数OnFunction与tmpObj对象的Event事件进行关联
            tmpObj.Event += new EventHandler(OnFunction);
 
            tmpObj.Function("7654321");
 
            Console.ReadLine();
        }
    }
}
结果:
1234567
7
6
5
4
3
2
1

示例
Example05Lib 项目的 Class1 
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example05Lib
{
    public class Class1
    {
        internal String strInternal = null;
        public String strPublic;
        internal protected String strInternalProtected = null;
    }
}
结果
Example05Lib 项目的 Class2 类可以访问到 Class1 的 strInternal 成员,当然也可以访问到 strInternalProtected 成员,因为他们在同一个程序集里
 
Example05 项目里的 Class3 类无法访问到 Class1 的 strInternal 成员,因为它们不在同一个程序集里。但却可以访问到 strInternalProtected 成员,因为 Class3 是 Class1 的继承类
 
Example05 项目的 Program 类既无法访问到 Class1 的 strInternal 成员,也无法访问到 strInternalProtected 成员,因为它们既不在同一个程序集里也不存在继承关系

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example06
{
    class Program
    {
        class A
        {
            public virtual void F()
            {
                Console.WriteLine("A.F");
            }
            public virtual void G()
            {
                Console.WriteLine("A.G");
            }
        }
        class B : A
        {
            public sealed override void F()
            {
                Console.WriteLine("B.F");
            }
            public override void G()
            {
                Console.WriteLine("B.G");
            }
        }
        class C : B
        {
            public override void G()
            {
                Console.WriteLine("C.G");
            }
        }
        static void Main(string[] args)
        {
            new A().F();
            new A().G();
            new B().F();
            new B().G();
            new C().F();
            new C().G();
 
            Console.ReadLine();
        }
    }
}
结果:
类 B 在继承类 A 时可以重写两个虚函数,如图所示:
 
由于类 B 中对 F 方法进行了密封, 类 C 在继承类 B 时只能重写一个函数,如图所示:
 
控制台输出结果,类 C 的方法 F 只能是输出 类B 中对该方法的实现:
A.F
A.G
B.F
B.G
B.F
C.G

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example07
{
    class Program
    {
        class BaseClass
        {
            public virtual void F()
            {
                Console.WriteLine("BaseClass.F");
            }
        }
        class DeriveClass : BaseClass
        {
            public override void F()
            {
                base.F();
                Console.WriteLine("DeriveClass.F");
            }
            public void Add(int Left, int Right)
            {
                Console.WriteLine("Add for Int: {0}", Left + Right);
            }
            public void Add(double Left, double Right)
            {
                Console.WriteLine("Add for int: {0}", Left + Right);
            }
        }
        static void Main(string[] args)
        {
            DeriveClass tmpObj = new DeriveClass();
            tmpObj.F();
            tmpObj.Add(1, 2);
            tmpObj.Add(1.1, 2.2);
 
            Console.ReadLine();
        }
    }
}
结果:
BaseClass.F
DeriveClass.F
Add for Int: 3
Add for int: 3.3

示例: 
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example08
{
    public class Point
    {
        private double x, y;
        public Point(double X, double Y)
        {
            x = X;
            y = Y;
        }
        //重写ToString方法方便输出
        public override string ToString()
        {
            return String.Format("X: {0} , Y: {1}", x, y);
        }
    }
    public class Points
    {
        Point[] points;
        public Points(Point[] Points)
        {
            points = Points;
        }
        public int PointNumber
        {
            get 
            { 
                return points.Length; 
            }
        }    
        //实现索引访问器
        public Point this[int Index]
        {
            get
            {
                return points[Index];
            }
        }
    }
 
    //感谢watson hua(http://huazhihao.cnblogs.com/)的指点
    //索引指示器的实质是含参属性,参数并不只限于int
    class WeatherOfWeek
    {
        public string this[int Index]
        {
            get
            {
                //注意case段使用return直接返回所以不需要break
                switch (Index)
                {
                    case 0:
                        {
                            return "Today is cloudy!";
                        }
                    case 5:
                        {
                            return "Today is thundershower!";
                        }
                    default:
                        {
                            return "Today is fine!";
                        }
                }
            }
        }
        public string this[string Day]
        {
            get
            {
                string TodayWeather = null;
                //switch的标准写法
                switch (Day)
                {
                    case "Sunday":
                        {
                            TodayWeather = "Today is cloudy!";
                            break;
                        }
                    case "Friday":
                        {
                            TodayWeather = "Today is thundershower!";
                            break;
                        }
                    default:
                        {
                            TodayWeather = "Today is fine!";
                            break;
                        }
                }
                return TodayWeather;
            }
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Point[] tmpPoints = new Point[10];
            for (int i = 0; i < tmpPoints.Length; i++)
            {
                tmpPoints[i] = new Point(i, Math.Sin(i));
            }
 
            Points tmpObj = new Points(tmpPoints);
            for (int i = 0; i < tmpObj.PointNumber; i++)
            {
                Console.WriteLine(tmpObj[i]);
            }
 
 
            string[] Week = new string[] { "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Staurday"};
            WeatherOfWeek tmpWeatherOfWeek = new WeatherOfWeek();
            for (int i = 0; i < 6; i++)
            {
                Console.WriteLine(tmpWeatherOfWeek[i]);
            }
            foreach (string tmpDay in Week)
            {
                Console.WriteLine(tmpWeatherOfWeek[tmpDay]);
            }
 
            Console.ReadLine();
        }
    }
}
结果:
X: 0 , Y: 0
X: 1 , Y: 0.841470984807897
X: 2 , Y: 0.909297426825682
X: 3 , Y: 0.141120008059867
X: 4 , Y: -0.756802495307928
X: 5 , Y: -0.958924274663138
X: 6 , Y: -0.279415498198926
X: 7 , Y: 0.656986598718789
X: 8 , Y: 0.989358246623382
X: 9 , Y: 0.412118485241757
Today is cloudy!
Today is fine!
Today is fine!
Today is fine!
Today is fine!
Today is thundershower!
Today is cloudy!
Today is fine!
Today is fine!
Today is fine!
Today is fine!
Today is thundershower!
Today is fine!

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example09
{
    class BaseClass
    {
        //基类设计者声明了一个PI的公共变量,方便进行运算
        public static double PI = 3.1415;
    }
    class DervieClass : BaseClass
    {
        //继承类发现该变量的值不能满足运算精度,于是可以通过new修饰符显式隐藏基类中的声明
        public new static double PI = 3.1415926;
    }
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine(BaseClass.PI);
            Console.WriteLine(DervieClass.PI);
 
            Console.ReadLine();
        }
    }
}
结果:
3.1415
3.1415926

示例:
    class BaseClass
    {
        public virtual void F()
        {
            Console.WriteLine("BaseClass.F");
        }
    }
    abstract class  DeriveClass1 : BaseClass
    {
        public abstract new void F();
    }
 
    //感谢watson hua(http://huazhihao.cnblogs.com/)的指点
    //是他提醒了我还可以用这种方法抽象重写基类的虚方法
    abstract class DeriveClass2 : BaseClass
    {
        public abstract override void F();
    }

示例:
    class BaseClass
    {
        public virtual void F()
        {
            Console.WriteLine("BaseClass.F");
        }
    }
    sealed class DeriveClass : BaseClass
    {
        //基类中的虚函数F被隐式的转化为非虚函数
 
        //密封类中不能再声明新的虚函数G
        //public virtual void G()
        //{
        //    Console.WriteLine("DeriveClass.G");
        //}
    }

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example14
{
    class BaseClass
    {
        public virtual void F()
        {
            Console.WriteLine("BaseClass.F");
        }
    }
    abstract class DeriveClass1 : BaseClass
    {
        //在这里, abstract是可以和override一起使用的
        public abstract override void F();
    }
    class Program
    {
        static void Main(string[] args)
        {
        }
    }
}

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example10
{
    class Class1
    {
        private double c;
        private string value;
 
        public double C
        {
            get
            {
                return c;
            }
        }
        public Class1(double c)
        {
            //限定同名的隐藏成员
            this.c = c;
        }
        public Class1(Class1 value)
        {
            //用对象本身实例化自己没有意义
            if (this != value)
            {
                c = value.C;
            }
        }
        public override string ToString()
        {
            //将对象本身做为参数
            return string.Format("{0} Celsius = {1} Fahrenheit", c, UnitTransClass.C2F(this));
        }
 
        //由于好奇,在这做了一个效率测试,想看看到底哪种方式访问成员变量更快,结论:区别不大。。。
        public string Test1()
        {
            long vTickCount = Environment.TickCount;
            for (int i = 0; i < 10000000; i++)
                this.value = i.ToString();
            return string.Format("Have this.: {0} MSEL", Environment.TickCount - vTickCount);
        }
        public string Test2()
        {
            long vTickCount = Environment.TickCount;
            for (int i = 0; i < 10000000; i++)
                value = i.ToString();
            return string.Format("Don't have this.: {0} MSEL", Environment.TickCount - vTickCount);
        }
    }
    class UnitTransClass
    {
        public static double C2F(Class1 value)
        {
            //摄氏到华氏的转换公式
            return 1.8 * value.C + 32;
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Class1 tmpObj = new Class1(37.5);
 
            Console.WriteLine(tmpObj);
 
            Console.WriteLine(tmpObj.Test1());
            Console.WriteLine(tmpObj.Test2());
 
            Console.ReadLine();
        }
    }
}

示例:
根据以上比较,我们可以得出一些轻量级的对象最好使用结构,但数据量大或有复杂处理逻辑对象最好使用类。
如:Geoemtry(GIS 里的一个概论,在 OGC 标准里有定义) 最好使用类,而 Geometry 中点的成员最好使用结构
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example16
{
    interface IPoint
    {
        double X
        {
            get;
            set;
        }
        double Y
        {
            get;
            set;
        }
        double Z
        {
            get;
            set;
        }
    }
    //结构也可以从接口继承
    struct Point: IPoint
    {
        private double x, y, z;
        //结构也可以增加构造函数
        public Point(double X, double Y, double Z)
        {
            this.x = X;
            this.y = Y;
            this.z = Z;
        }
        public double X
        {
            get { return x; }
            set { x = value; }
        }
        public double Y
        {
            get { return x; }
            set { x = value; }
        }
        public double Z
        {
            get { return x; }
            set { x = value; }
        }
    }
    //在此简化了点状Geometry的设计,实际产品中还包含Project(坐标变换)等复杂操作
    class PointGeometry
    {
        private Point value;
        
        public PointGeometry(double X, double Y, double Z)
        {
            value = new Point(X, Y, Z);
        }
        public PointGeometry(Point value)
        {
            //结构的赋值将分配新的内存
            this.value = value;
        }
        public double X
        {
            get { return value.X; }
            set { this.value.X = value; }
        }
        public double Y
        {
            get { return value.Y; }
            set { this.value.Y = value; }
        }
        public double Z
       {
            get { return value.Z; }
            set { this.value.Z = value; }
        }
        public static PointGeometry operator +(PointGeometry Left, PointGeometry Rigth)
        {
            return new PointGeometry(Left.X + Rigth.X, Left.Y + Rigth.Y, Left.Z + Rigth.Z);
        }
        public override string ToString()
        {
            return string.Format("X: {0}, Y: {1}, Z: {2}", value.X, value.Y, value.Z);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            Point tmpPoint = new Point(1, 2, 3);
 
            PointGeometry tmpPG1 = new PointGeometry(tmpPoint);
            PointGeometry tmpPG2 = new PointGeometry(tmpPoint);
            tmpPG2.X = 4;
            tmpPG2.Y = 5;
            tmpPG2.Z = 6;
 
            //由于结构是值类型,tmpPG1 和 tmpPG2 的坐标并不一样
            Console.WriteLine(tmpPG1);
            Console.WriteLine(tmpPG2);
 
            //由于类是引用类型,对tmpPG1坐标修改后影响到了tmpPG3
            PointGeometry tmpPG3 = tmpPG1;
            tmpPG1.X = 7;
            tmpPG1.Y = 8;
            tmpPG1.Z = 9;
            Console.WriteLine(tmpPG1);
            Console.WriteLine(tmpPG3);
 
            Console.ReadLine();
        }
    }
}
结果:
X: 1, Y: 2, Z: 3
X: 4, Y: 5, Z: 6
X: 7, Y: 8, Z: 9
X: 7, Y: 8, Z: 9

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example17
{
    class Program
    {
        //一个完整的接口声明示例
        interface IExample
        {
            //属性
            string P
            {
                get;
                set;
            }
            //方法
            string F(int Value);
            //事件
            event EventHandler E;
            //索引指示器
            string this[int Index]
            {
                get;
                set;
            }
        }
        interface IA
        {
            int Count { get; set;}
        }
        interface IB
        {
            int Count();
        }
        //IC接口从IA和IB多重继承
        interface IC : IA, IB
        {
        }
        class C : IC
        {
            private int count = 100;
            //显式声明实现IA接口中的Count属性
            int IA.Count
            {
                get { return 100; }
                set { count = value; }
            }
            //显式声明实现IB接口中的Count方法
            int IB.Count()
            {
                return count * count;
            }
        }
        static void Main(string[] args)
        {
            C tmpObj = new C();
 
            //调用时也要显式转换
            Console.WriteLine("Count property: {0}", ((IA)tmpObj).Count);
            Console.WriteLine("Count function: {0}", ((IB)tmpObj).Count());
 
            Console.ReadLine();
        }
    }
}
结果:
Count property: 100
Count function: 10000

示例:
Class1.cs: 
using System;
using System.Collections.Generic;
using System.Text;
 
namespace com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib01
{
    class Class1
    {
        public override string ToString()
        {
            return "com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib01's Class1";
        }
    }
}
Class2.cs: 
using System;
using System.Collections.Generic;
using System.Text;
 
namespace com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib02
{
    class Class1
    {
        public override string ToString()
        {
            return "com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib02's Class1";
        }
    }
}
主单元(Program.cs):
using System;
using System.Collections.Generic;
using System.Text;
 
//使用别名指示符解决同名类型的冲突
//在所有命名空间最外层定义,作用域为整个单元文件
using Lib01Class1 = com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib01.Class1;
using Lib02Class2 = com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib02.Class1;
 
namespace Example19
{
    namespace Test1
    {
        //Test1Class1在Test1命名空间内定义,作用域仅在Test1之内
        using Test1Class1 = com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib01.Class1;
 
        class Class1
        {
            //Lib01Class1和Lib02Class2在这可以正常使用
            Lib01Class1 tmpObj1 = new Lib01Class1();
            Lib02Class2 tmpObj2 = new Lib02Class2();
            //TestClass1在这可以正常使用
            Test1Class1 tmpObj3 = new Test1Class1();
        }
    }
    namespace Test2
    {
        using Test1Class2 = com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib01.Class1;
 
        class Program
        {
            static void Main(string[] args)
            {
                //Lib01Class1和Lib02Class2在这可以正常使用
                Lib01Class1 tmpObj1 = new Lib01Class1();
                Lib02Class2 tmpObj2 = new Lib02Class2();
 
                //注意这里,TestClass1在这不可以正常使用。
                //因为,在Test2命名空间内不能使用Test1命名空间定义的别名
                //Test1Class1 tmpObj3 = new Test1Class1();
                
                //TestClass2在这可以正常使用
                Test1Class2 tmpObj3 = new Test1Class2();
 
                Console.WriteLine(tmpObj1);
                Console.WriteLine(tmpObj2);
                Console.WriteLine(tmpObj3);
 
                Console.ReadLine();
            }
        }
    }
}

结果:
com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib01's Class1
com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib02's Class1
com.nblogs.reonlyrun.CSharp25QExample.Example19.Lib01's Class1

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example20
{
    class Program
    {
        class Class1 : IDisposable
        {
            //析构函数,编译后变成 protected void Finalize(),GC会在回收对象前会调用调用该方法
            ~Class1()
            {
                Dispose(false);
            }
 
            //通过实现该接口,客户可以显式地释放对象,而不需要等待GC来释放资源,据说那样会降低效率
            void IDisposable.Dispose()
            {
                Dispose(true);
            }
 
            //将释放非托管资源设计成一个虚函数,提供在继承类中释放基类的资源的能力
            protected virtual void ReleaseUnmanageResources()
            {
                //Do something...
            }
 
            //私有函数用以释放非托管资源
            private void Dispose(bool disposing)
            {
                ReleaseUnmanageResources();
 
                //为true时表示是客户显式调用了释放函数,需通知GC不要再调用对象的Finalize方法
                //为false时肯定是GC调用了对象的Finalize方法,所以没有必要再告诉GC你不要调用我的Finalize方法啦
                if (disposing)
                {
                    GC.SuppressFinalize(this);
                }
            } 
        }
        static void Main(string[] args)
        {
            //tmpObj1没有手工释放资源,就等着GC来慢慢的释放它吧
            Class1 tmpObj1 = new Class1();
 
            //tmpObj2调用了Dispose方法,传说比等着GC来释放它效率要调一些
            //个人认为是因为要逐个对象的查看其元数据,以确认是否实现了Dispose方法吧
            //当然最重要的是我们可以自己确定释放的时间以节省内存,优化程序运行效率
            Class1 tmpObj2 = new Class1();
            ((IDisposable)tmpObj2).Dispose();
        }
    }
}

示例: 
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example22
{
    class Program
    {
        static void Main(string[] args)
        {
            const int cycle = 10000;
 
            long vTickCount = Environment.TickCount;
            String str = null;
            for (int i = 0; i < cycle; i++)
                str += i.ToString();
            Console.WriteLine("String: {0} MSEL", Environment.TickCount - vTickCount);
 
            vTickCount = Environment.TickCount;
            //看到这个变量名我就生气,奇怪为什么大家都使它呢? :)
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < cycle; i++)
                sb.Append(i);
            Console.WriteLine("StringBuilder: {0} MSEL", Environment.TickCount - vTickCount);
 
            string tmpStr1 = "A";
            string tmpStr2 = tmpStr1;
            Console.WriteLine(tmpStr1);
            Console.WriteLine(tmpStr2);
            //注意后面的输出结果,tmpStr1的值改变并未影响到tmpStr2的值
            tmpStr1 = "B";
            Console.WriteLine(tmpStr1);
            Console.WriteLine(tmpStr2);
 
            Console.ReadLine();
        }
    }
}
结果:
String: 375 MSEL
StringBuilder: 16 MSEL
A
A
B
A

示例: 
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example23
{
    class Program
    {
        //本例灵感来源于大话西游经典台词“神仙?妖怪?”--主要是我实在想不出什么好例子了
        class Immortal
        {
            public string name;
            public Immortal(string Name)
            {
                name = Name;
            }
            public static implicit operator Monster(Immortal value)
            {
                return new Monster(value.name + ":神仙变妖怪?偷偷下凡即可。。。");
            }
        }
        class Monster
        {
            public string name;
            public Monster(string Name)
            {
                name = Name;
            }
            public static explicit operator Immortal(Monster value)
            {
                return new Immortal(value.name + ":妖怪想当神仙?再去修炼五百年!");
            }
        }
        static void Main(string[] args)
        {
            Immortal tmpImmortal = new Immortal("紫霞仙子");
            //隐式转换
            Monster tmpObj1 = tmpImmortal;
            Console.WriteLine(tmpObj1.name);
 
            Monster tmpMonster = new Monster("孙悟空");
            //显式转换
            Immortal tmpObj2 = (Immortal)tmpMonster;
            Console.WriteLine(tmpObj2.name);
 
            Console.ReadLine();
        }
    }
}
结果:
紫霞仙子:神仙变妖怪?偷偷下凡即可。。。
孙悟空:妖怪想当神仙?再去修炼五百年!

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace ConsoleApplication1
{
    class App
    {
        //第一个参数必须是整型,但后面的参数个数是可变的。
        //而且由于定的是object数组,所有的数据类型都可以做为参数传入
        public static void UseParams(int id, params object[] list)
        {
            Console.WriteLine(id);
            for (int i = 0; i < list.Length; i++)
            {
                Console.WriteLine(list[i]);
            }
        }
 
        static void Main()
        {
            //可变参数部分传入了三个参数,都是字符串类型
            UseParams(1, "a", "b", "c");
            //可变参数部分传入了四个参数,分别为字符串、整数、浮点数和双精度浮点数数组
            UseParams(2, "d", 100, 33.33, new double[] { 1.1, 2.2 });
 
            Console.ReadLine();
        }
    }
}
结果:
1
a
b
c
2
d
100
33.33
System.Double[]

示例:
using System;
using System.Collections.Generic;
using System.Text;
 
namespace Example25Lib
{
    public class Class1
    {
        private string name;
        private int age;
 
        //如果显式的声明了无参数构造函数,客户端只需要用程序集的CreateInstance即可实例化该类
        //在此特意不实现,以便在客户调用端体现构造函数的反射实现
        //public Class1()
        //{
        //}
        public Class1(string Name, int Age)
        {
            name = Name;
            age = Age;
        }
        public void ChangeName(string NewName)
        {
            name = NewName;
        }
        public void ChangeAge(int NewAge)
        {
            age = NewAge;
        }
        public override string ToString()
        {
            return string.Format("Name: {0}, Age: {1}", name, age);
        }
    }
}
反射实例化对象并调用其方法,属性和事件的反射调用略去
using System;
using System.Collections.Generic;
using System.Text;
 
//注意添加该反射的命名空间
using System.Reflection;
 
namespace Example25
{
    class Program
    {
        static void Main(string[] args)
        {
            //加载程序集
            Assembly tmpAss = Assembly.LoadFile(AppDomain.CurrentDomain.BaseDirectory + "Example25Lib.dll");
 
            //遍历程序集内所有的类型,并实例化
            Type[] tmpTypes = tmpAss.GetTypes();
            foreach (Type tmpType in tmpTypes)
            {
                //获取第一个类型的构造函数信息
                ConstructorInfo[] tmpConsInfos = tmpType.GetConstructors();
                foreach (ConstructorInfo tmpConsInfo in tmpConsInfos)
                {
                    //为构造函数生成调用的参数集合
                    ParameterInfo[] tmpParamInfos = tmpConsInfo.GetParameters(); 
                    object[] tmpParams = new object[tmpParamInfos.Length];
                    for (int i = 0; i < tmpParamInfos.Length; i++)
                    {
                        tmpParams[i] = tmpAss.CreateInstance(tmpParamInfos[i].ParameterType.FullName);
                        if (tmpParamInfos[i].ParameterType.FullName == "System.String")
                        {
                            tmpParams[i] = "Clark";
                        }
                    }
 
                    //实例化对象
                    object tmpObj = tmpConsInfo.Invoke(tmpParams);
                    Console.WriteLine(tmpObj);
 
                    //获取所有方法并执行
                    foreach (MethodInfo tmpMethod in tmpType.GetMethods())
                    {
                        //为方法的调用创建参数集合
                        tmpParamInfos = tmpMethod.GetParameters();
                        tmpParams = new object[tmpParamInfos.Length];
                        for (int i = 0; i < tmpParamInfos.Length; i++)
                        {
                            tmpParams[i] = tmpAss.CreateInstance(tmpParamInfos[i].ParameterType.FullName);
                            if (tmpParamInfos[i].ParameterType.FullName == "System.String")
                            {
                                tmpParams[i] = "Clark Zheng";
                            }
                            if (tmpParamInfos[i].ParameterType.FullName == "System.Int32")
                            {
                                tmpParams[i] = 27;
                            }
                        }
                        tmpMethod.Invoke(tmpObj, tmpParams);
                    }
 
                    //调用完方法后再次打印对象,比较结果
                    Console.WriteLine(tmpObj);
                }
            }
 
            Console.ReadLine();
        }
    }
}
结果:
Name: Clark, Age: 0
Name: Clark Zheng, Age: 27

抱歉!评论已关闭.