C#常用知识点简单回顾(有图有真相)

1)传值调用与引用调用
复制代码 代码如下:
using System;
class MethodCall
{
public static void Main()
{

int a = 1, b = 2, c;
Console.WriteLine("Before Method Call : a = {0}, b = {1}, c 未赋值", a, b);
AMethod(a, ref b, out c);
Console.WriteLine("After Method Call : a = {0}, b = {1}, c = {2}", a, b, c);
Console.Read();
}
public static void AMethod(int x, ref int y, out int z)
{
x = 110;
y = 120;
z = 119;
}
}

效果图：

 2)打印三角形
复制代码 代码如下:
using System;
public class Hello
{
public static void Main()
{
Console.Write("请输入行数:");
int lines = int.Parse(Console.ReadLine());
Console.WriteLine("");
for(int i=1; i<=lines ; i++)
{
for(int k=1; k<= lines-i; k++)
Console.Write(" ");
for(int j=1; j<=i*2+1; j++)
Console.Write("*");
Console.WriteLine("");
}
Console.ReadLine();
}
}

效果图：

 3)递归求阶乘
复制代码 代码如下:
using System;
class Factor
{
public static void Main()
{
for(int i=1; i<=10; i++)
Console.WriteLine("{0} 的阶乘是 {1}",i, Factorial(i));
Console.Read();
}
public static long Factorial(long n)
{
if(n == 1)
return 1;
else
return n * Factorial(n-1);
}
}

效果图：

4)多态性
复制代码 代码如下:
using System;
class Car
{
public virtual void Drive()
{ Console.WriteLine("Drive Car"); }
}
class Truck : Car
{
public override void Drive()
{ Console.WriteLine("Drive Truck"); }
}
class Client
{
public static void Main()
{
Car c = new Truck();
c.Drive(); //多态性决定着将调用Truck的Drive方法
Console.Read();
}
}

效果图：

5)方法重载
复制代码 代码如下:
using System;
class Client
{
public static void Main()
{
//重载是指方法名相同，方法的签名不同
Console.WriteLine(Add(100,50));
Console.WriteLine(Add("100","50"));
Console.Read();
}
public static string Add(string a, string b)
{
return a + " add " + b;
}
public static int Add(int a, int b)
{
return a+b;
}
}

效果图：

6)构造函数
复制代码 代码如下:
using System;
public class Person
{
public string name = "";
public int age = 0;
//默认构造函数
public Person()
{
}
//构造函数重载(1)
public Person(int Age)
{
this.age = Age;
}
//构造函数重载(2)
public Person(int Age, string Name)
{
this.age = Age;
this.name = Name;
}
public void ShowInfo()
{
Console.WriteLine("姓名:" + name);
Console.WriteLine("年龄:" + age);
}
}
class Client
{
public static void Main()
{
Person p1 = new Person();
p1.ShowInfo();
Console.WriteLine("*************************");
Person p2 = new Person(25);
p2.ShowInfo();
Console.WriteLine("*************************");
Person p3 = new Person(25, "爱智旮旯");
p3.ShowInfo();
Console.Read();
}
}

效果图：

7)静态与非静态
复制代码 代码如下:
using System;
class StaticHello
{
public static void SayHello()
{ Console.WriteLine("Static Hello"); }
}
class NonStaticHello
{
public void SayHello()
{ Console.WriteLine("Non Static Hello"); }
}
class Client
{
public static void Main()
{
//静态方法调用应当使用 “类名.方法”
StaticHello.SayHello();
//非静态方法调用应当使用 “实例名称.方法”
NonStaticHello h = new NonStaticHello();
h.SayHello();
Console.Read();
}
}

效果图：

8)九九表
复制代码 代码如下:
using System;
public class JiuJiuBiao
{
public static void Main(string[] args)
{
int i,j;
for(i=1; i<10; i++)
{
for(j=1; j<10; j++)
{
Console.Write("{0:D1}*{1:D1}={2,2} ", i, j, i*j);
}
Console.WriteLine("");
}
Console.ReadLine();
}
}

效果图：

9)冒泡法排序
复制代码 代码如下:
using System;
class ArraySort
{
public static void Main()
{
int[] d = {10,15,21,43,17,98,2,74,63,10};
int temp;
//冒泡法排序
for(int i=0; ifor(int j=i+1; jif(d[i]{
temp = d[i];
d[i]=d[j];
d[j]=temp;
}
//输出排序结果
foreach(int i in d)
Console.Write("{0}, ", i);
Console.Read();
}
}

效果图：

10)求质数
复制代码 代码如下:
using System;
class Factor
{
public static void Main()
{
for(int i=1; i<=100; i++)
if(IsPrime(i))
Console.WriteLine(i);
Console.Read();
}
public static bool IsPrime(int n)
{
for(int i=2; i<=Math.Sqrt(n); i++)
if(n%i == 0)
return false;
return true;
}
}

效果图：

11)使用接口排序(1)
复制代码 代码如下:
using System;
using System.Collections;
public class Person : IComparable
{
public int ID;
public string Rank;
public Person(int id, string rank)
{ this.ID=id; this.Rank = rank; }
#region IComparable Members

public int CompareTo(object obj)
{
Person p = (Person)obj;
return this.ID.CompareTo(p.ID);
}
#endregion
}
class SortArrayList
{
static void Main(string[] args)
{
ArrayList list = new ArrayList();
list.Add(new Person(6, "排长"));
list.Add(new Person(3, "团长"));
list.Add(new Person(4, "司令"));
list.Add(new Person(5, "旅长"));
list.Add(new Person(7, "连长"));
list.Add(new Person(1, "军长"));
list.Add(new Person(2, "营长"));
list.Add(new Person(8, "师长"));
list.Sort();
Console.WriteLine("After Sorting");
foreach (Person person in list)
{
Console.WriteLine("ID: " + person.ID.ToString() + ", Rank: " + person.Rank);
}
}
}

效果图：

12)使用接口排序(2)
复制代码 代码如下:
using System;
using System.Collections;
public enum enuSortOrder
{IDAsc, IDDesc, RankAsc, RankDesc}
public class Person : IComparable
{
public static enuSortOrder intSortOrder = enuSortOrder.IDAsc;
public int ID;
public string Rank;
public Person(int id, string rank)
{ this.ID=id; this.Rank = rank; }
#region IComparable Members

public int CompareTo(object obj)
{
Person p = (Person)obj;
switch ((int)intSortOrder)
{
case (int)enuSortOrder.IDAsc:
return this.ID.CompareTo(p.ID);
case (int)enuSortOrder.IDDesc:
return p.ID.CompareTo(this.ID);
case (int)enuSortOrder.RankAsc:
return RankCompare(this.Rank, p.Rank);
case (int)enuSortOrder.RankDesc:
return RankCompare(p.Rank, this.Rank);
default:
return this.ID.CompareTo(p.ID);
}
}
private int RankCompare(string rank1, string rank2)
{
int intRank1 = ConvertRankToInt(rank1);
int intRank2 = ConvertRankToInt(rank2);
if(intRank1 < intRank2)
return -1;
else if(intRank1 == intRank2)
return 0;
else
return 1;
}
private int ConvertRankToInt(string rank)
{
if(rank == "司令")
return 8;
else if(rank == "军长")
return 7;
else if(rank == "师长")
return 6;
else if(rank == "旅长")
return 5;
else if(rank == "团长")
return 4;
else if(rank == "营长")
return 3;
else if(rank == "连长")
return 2;
else
return 1;
}
#endregion
}
class SortArrayList
{
static void Main(string[] args)
{
ArrayList list = new ArrayList();
list.Add(new Person(6, "排长"));
list.Add(new Person(3, "团长"));
list.Add(new Person(4, "司令"));
list.Add(new Person(5, "旅长"));
list.Add(new Person(7, "连长"));
list.Add(new Person(1, "军长"));
list.Add(new Person(2, "营长"));
list.Add(new Person(8, "师长"));
list.Sort();
Console.WriteLine("Sort By ID Asc:");
foreach (Person person in list)
{
Console.WriteLine("ID: " + person.ID.ToString() + ", Rank: " + person.Rank);
}
Console.WriteLine("----------------------------");
Console.WriteLine("Sort By ID Desc:");
Person.intSortOrder = enuSortOrder.IDDesc;
list.Sort();
foreach (Person person in list)
{
Console.WriteLine("ID: " + person.ID.ToString() + ", Rank: " + person.Rank);
}
Console.WriteLine("----------------------------");
Console.WriteLine("Sort By Rank Asc:");
Person.intSortOrder = enuSortOrder.RankAsc;
list.Sort();
foreach (Person person in list)
{
Console.WriteLine("ID: " + person.ID.ToString() + ", Rank: " + person.Rank);
}
Console.WriteLine("----------------------------");
Console.WriteLine("Sort By Rank Desc:");
Person.intSortOrder = enuSortOrder.RankDesc;
list.Sort();
foreach (Person person in list)
{
Console.WriteLine("ID: " + person.ID.ToString() + ", Rank: " + person.Rank);
}
}
}

效果图：

13)属性、方法作用范围
复制代码 代码如下:
using System;
class base
{

public string name = "Tom";
private double salary = 1500;
protected int age = 20;
public virtual void ShowInfo()
{
Console.WriteLine(this.name); //可以，因为name是 public 型的
Console.WriteLine(this.salary); //可以，salary是private型，在base类中可以访问
Console.WriteLine(this.age); //可以，因为age是protected型，在子类中可以访问
}
}
class Derived : base
{
public override void ShowInfo()
{
Console.WriteLine(this.name); //可以，因为name是 public 型的
//Console.WriteLine(this.salary); //不可以，salary是private型，超出base就无法访问
Console.WriteLine(this.age); //可以，因为age是protected型，在子类中可以访问
}
}
class Client
{
public static void Main()
{
base b = new base();
Console.WriteLine(b.name); //可以，因为name是 public 型的
//Console.WriteLine(this.salary); //不可以，salary是private型，超出base就无法访问
//Console.WriteLine(this.age); //不可以，因为age是protected型，Client不是base的子类
Console.WriteLine("==========================");
b.ShowInfo();
Console.WriteLine("==========================");
Derived d = new Derived();
d.ShowInfo();
}
}

效果图：

15)字段与属性
复制代码 代码如下:
using System;
class SumToHundred
{
public static void Main()
{
int sum=0;
for(int i=1; i<=100; i++)
sum += i;
Console.WriteLine(sum);
}
}

pic
复制代码 代码如下:
using System;
class Account
{
private double balance = 0; //字段
public double Balance //属性
{
get { return balance; }
set { balance = value;}
}

public void Deposit(double n)
{ this.balance += n; }
public void WithDraw(double n)
{ this.balance -= n; }
}
class Client
{
public static void Main()
{
Account a = new Account();
a.Balance = 1000; // 可以读写属性，因为属性Balance是public型的
//a.balance = 1000; //不可以读写字段，因为字段balance是private型的
a.WithDraw(500);
a.Deposit(2000);
Console.WriteLine(a.Balance);
}
}