C#课本例题第三章

一、对象的引用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0301
{
    class Tree
    {
        internal int height;
    }
    public class Assignment
        
    {
        static void Main(string[] args)
        {
            Tree t1;
            Tree t2 = new Tree();
            Tree t3 = new Tree();
            t1 = t2;
            t2.height = 3;
            t3.height = 3;
            if (t1 == t2) Console.WriteLine("t1=t2");
            if (t2 == t3) Console.WriteLine("t2=t3");
            Console.ReadLine();
        }
    }
}

二、声明一个类的方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0302
{
    class Program
    {
        static int Add(int x,int y)
        {
            return x + y;
        }
        static void Main(string[] args)
        {
            Console.WriteLine("123+456={0}", Add(123, 456));
            Console.ReadLine();
        }
    }
}

三、方法中值参数的应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0303
{
    class Program
    {
        static void Swap(int a, int b)
        {
            int temp = a;
            a = b;
            b = temp;
        }
        static void Main(string[] args)
        {
            int i = 1,j = 2;
            Swap( i,j);
            Console.WriteLine("i={0};j={1}", i, j);
            Console.WriteLine( ) ;
            Console.WriteLine("Swap并没有对数据进行交换，拥有值参数的方法，不改变此方法外部的数据");
            Console.ReadLine();

        }
    }
}

四、方法中引用参数的应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0303
{
    class Program
    {
        static void Swap(ref int a, ref int b)
        {
            int temp = a;
            a = b;
            b = temp;
        }
        static void Main(string[] args)
        {
            int i = 1, j = 2;
            Swap(ref i, ref j);
            Console.WriteLine("i={0};j={1}", i, j);
            Console.WriteLine();
            Console.WriteLine("Swap采用应用参数后，ij 两值调换");
            Console.ReadLine();

        }
    }
}

方法中输出参数的应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0305
{
    class Program
    {
        static void SplitPath(string path, out string dirname, out string filename)
        {
            int n = path.Length;
            while (n > 0)
            {
                char ch = path[n - 1];
                if (ch == '\' | ch == '/' || ch == ':') break;

                n--;
            }
                dirname = path.Substring(0, n);
                filename = path.Substring(n);
            }

            static void Main(string[] args)
            {
                string dname, fname;
                SplitPath("c:\MyDocuments\简历.doc", out dname, out fname);
                Console.WriteLine(dname);
                Console.WriteLine(fname);
                Console.ReadLine();

            }
        
    } }

六、构造函数的使用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0306
{
    public class Quad
    {
        protected double width, height;
        public Quad(double d)
        {
            width = d;
            height = d;
        }
        public Quad(double w, double h)
        {
            width = w;
            height = h;
        }
        public double Area()
        {
            return width * height;
        }
    }
    public class demo
    {
 static void Main(string[] args)
        {
            Quad q1 = new Quad(4);
            Quad q2 = new Quad(2, 3);
            Console.WriteLine("q1的面积={0}", q1.Area());
            Console.WriteLine("q2的面积={0}", q2.Area());
            Console.ReadLine();

        }
    }
       
    }

七、方法的重载

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0307
{
    class Tree
    {
        int height;
        public  Tree()
        {
            Console.WriteLine("种植一棵幼苗");
             height = 0;

        }
        public Tree(int i)
        {
            Console.WriteLine("树在生长，现在高度是" + i + "尺");
            height = i;
        }
        internal void info()
        {
            Console.WriteLine("现在是" + height + "尺");
        }
        internal void info(string s)
        {
            Console.WriteLine(s + ":是" + height + "尺");
        }
    }
   public class demo
    {
        static void Main(string[] args)
        {
            new Tree();
            for(int i=0;i<4;i++)
            {
                Tree t = new Tree(i);
                t.info();
                t.info("重载方法");
            }
            Console.ReadLine();
        }
    }
}

八、继承的实例

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0308
{
    public class Parent
    {
        string parentString;

        public Parent()
        {
            Console.WriteLine("父体类");
        }
        public Parent(string myString)
        {
            parentString = myString;
            Console.WriteLine(parentString);
        }
        public void Print()
        {
            Console.WriteLine("这里是父类");
        }
    }
    public class Child : Parent
    {
        public Child()
            : base("从父类")
        {
            Console.WriteLine("子体类");
        }
        public void Print()
        {
            base.Print();
            Console.WriteLine("这里是子类");
        }


        static void Main(string[] args)
        {
            Child child = new Child();
            child.Print();
            ((Parent)child).Print();
            Console.ReadLine();
        }
    }
}

九、覆盖的应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0309
{
    class Car
    {
        public int wheels;
        protected float weight;
        public Car()
        {
            ;
        }
        public Car(int w, float g)
        {
            wheels = w;
            weight = g;
        }
        public void speak()
        {
            Console.WriteLine("Car Balabala");
        } 
    }
    class auto:Car
    {
        int passenagers;
        public auto(int w,float g,int p)
            :base(w,g)
        {
            wheels = w;
            weight=g;
            passenagers = p;
        }
        new public void speak()
        {
            Console.WriteLine("bibi");

        }
        static void Main(string[] args)
        {
            auto car = new auto(10, 10, 20);
            car.speak();
            Console.ReadLine();
        }
        
    }
        
    }

十、多态的应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0310
{
    public class Rectangle
    {
        protected double a, b;
        public Rectangle() { }
        public Rectangle(double a, double b)
        {
            this.a = a;
            this.b = b;
        }
        public virtual double Area()
        {
            return a * b;
        }
    }
    public class Cylinder : Rectangle
    {
        public Cylinder(double h, double r):base(h,r) { }
        public override double Area()
        {
            return 2 * Math.PI * b * b + 2 * Math.PI * a * b;
        }
    }
    public class Test
    { 
        static void Main(string[] args)
    {
            Rectangle r = new Rectangle(1, 10);
            Cylinder c = new Cylinder(4, 2);
            Console.WriteLine("矩形的面积：{0}", r.Area());
            Console.WriteLine("圆柱体的表面积：{0}", c.Area());
            Console.ReadLine();
    }
}
}

十一、域的应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0311
{
    public class FieldTest
    {
        public static int n = 1;
        public int m = 1;
        public FieldTest()
        {
            n++;
            m++;
        }
    }
    class ex0309
    { 
        static void Main(string[] args)
        {
            Console.WriteLine(FieldTest.n);
            FieldTest t1=new FieldTest();
            Console.WriteLine(FieldTest.n);
            Console.WriteLine(t1.m);
            FieldTest t2 = new FieldTest();
            Console.WriteLine(FieldTest.n);
            Console.WriteLine(t2.m);
            Console.ReadLine();
        }
    }
}

十二、属性的应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0312
{
    public class Employee
    {
        private string name;
        private long idcard;
        private double salary;
        private double increase;

        public string Name
        {
            get { return name; }
            set { name = value; }
        }

        public double Salary
        {
            get { return salary; }
            set { salary = value; }
        }
        public long ID
        {
            get { return idcard; }
            set { idcard = value; }
        }
        public void Print()
        {
            Console.WriteLine("姓名：{0}", name);
            Console.WriteLine("ID:{0}", idcard);
            Console.WriteLine("工资：{0}", salary);
            Console.WriteLine("加薪：{0}",increase);
        }

        public void raise(double percent)
        {
            increase = percent * salary;
        }
        public Employee(string n,long id,double s)
        {
            name = n;
            idcard = id;
            salary = s;
        }
    }
    public class PropertyTest
    {
        static void Main(string[] args)
        {
            Employee e = new Employee("张三", 1000001, 2000.0);
            e.raise(0.07);
            e.Print();
            e.Name = "李四";
            e.Salary = 6000.0;
            e.raise(0.05);
            Console.WriteLine(e.Name);
            e.Print();
            Console.ReadLine();

        }
    }
}

十三、设计一个“三角形”类，其中包括公共数据域三个顶点坐标，判断是否为三角形，并求解其面积

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0313
{
    class SJX
    {
        public int Px1, Px2, Px3, PY1, PY2, PY3;
        public bool IsSJX()
        {
            if ((PY3 - PY2) * (Px3 - Px1) == (PY3 - PY1) * (Px3 - Px2))
                return false;
            else
                return true;
        }
        public double Mj()
        {
            return Math.Abs(Px1 * PY2 + Px2 * PY3 + Px3 * PY1 - PY1 * Px2 - PY2 * Px3 - PY3 * Px1) / 2.0;
        }
        static void Main(string[] args)
        {
            SJX sjx = new SJX();
            Console.Write("请输入第1点X: ");sjx.Px1 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第2点X: "); sjx.Px2 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第3点X: "); sjx.Px3 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第1点Y: "); sjx.PY1 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第2点Y: "); sjx.PY2 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第3点Y: "); sjx.PY3 = Convert.ToInt16(Console.ReadLine());
            if (sjx.IsSJX())
            {
                Console.WriteLine("该△面积={0}", sjx.Mj());
                Console.ReadLine();
            }
            else
            {
                Console.WriteLine("该点不能构成三角形");
                Console.ReadLine();
            }

        }
    }
    
}

继续十三，定义一个类DYSJX（等腰三角形），继承SJX类，判断是否为等腰三角形，并求其面积。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ex0314
{
    class SJX
    {
        public int Px1, Px2, Px3, PY1, PY2, PY3;
        public bool IsSJX()
        {
            if ((PY3 - PY2) * (Px3 - Px1) == (PY3 - PY1) * (Px3 - Px2))
                return false;
            else
                return true;
        }
        public double Mj()
        {
            return Math.Abs(Px1 * PY2 + Px2 * PY3 + Px3 * PY1 - PY1 * Px2 - PY2 * Px3 - PY3 * Px1) / 2.0;
        }
    }
    class DYSJX : SJX
    {
        public bool IsDYSJX()
        {
            double l1, l2, l3;
            l1=Math.Sqrt(Math.Abs((Px1-Px2)*(Px1-Px2)-(PY1-PY2)*(PY1-PY2)));
            l2 = Math.Sqrt(Math.Abs((Px1 - Px3) * (Px1 - Px3) - (PY1 - PY3) * (PY1 - PY3)));
            l3 = Math.Sqrt(Math.Abs((Px3 - Px2) * (Px3 - Px2) - (PY3 - PY2) * (PY3 - PY2)));
            if ((l1 == l2) || (l2 == l3) || (l1 == l3))
                return true;
            else
                return false;
        }
    }
    class Program
    { 
        static void Main(string[] args)
        {
            DYSJX dysjx = new DYSJX();
            Console.Write("请输入第1点X: "); dysjx.Px1 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第2点X: "); dysjx.Px2 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第3点X: "); dysjx.Px3 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第1点Y: "); dysjx.PY1 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第2点Y: "); dysjx.PY2 = Convert.ToInt16(Console.ReadLine());
            Console.Write("请输入第3点Y: "); dysjx.PY3 = Convert.ToInt16(Console.ReadLine());
            if (dysjx.IsSJX())
            {
                Console.WriteLine("该△面积={0}", dysjx.Mj());
                if (dysjx.IsDYSJX())
                    Console.WriteLine("是等腰三角形");
                else
                    Console.WriteLine("不是等腰三角形");

                    Console.ReadLine();
            }
            else
            {
                Console.WriteLine("该点不能构成三角形");
                Console.ReadLine();
            }

        }
    }

}

C#课本例题第三章

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