C#常用知识点简单回顾(有图有真相)

using System;
class MethodCall
{
public static void Main()
{
/*
* 参数类型分为 in, ref, out 三种，默认为 in。
* in 类型在子方法中修改了对应变量后，主方法中的值不会发生改变。
* ref 类型在子方法中修改了对应变量后，主方法中的值也会发生改变。
* out 主方法中对应的变量不需要初始化。
*
*/
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;
}
}

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();
}
}

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);
}
}

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();
}
}

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;
}
}

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();
}
}

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();
}
}

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();
}
}

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; i<d.Length; i++)
for(int j=i+1; j<d.Length; j++)
if(d[i]<d[j])
{
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();
}
}

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;
}
}

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
/*
* IComparable 接口只有一个方法: CompareTo。CompareTo方法
* 只接收一个object类型的参数，这意味着它可以接收任何类
* 型的数据（object是所有类的父类），这个方法会返回一
* 整型数值，含义如下：
*
* 1) 小于零，当前实例（this）小于obj对象
* 2) 等于零，当前实例（this）等于obj对象
* 3) 大于零，当前实例（this）大于obj对象
*
* Int32,Int16...,String,Decimal等数据类型都已经实现了IComparable接口
*/
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);
}
}
}

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
/*
* IComparable 接口只有一个方法: CompareTo。CompareTo方法
* 只接收一个object类型的参数，这意味着它可以接收任何类
* 型的数据（object是所有类的父类），这个方法会返回一
* 整型数值，含义如下：
*
* 1) 小于零，当前实例（this）小于obj对象
* 2) 等于零，当前实例（this）等于obj对象
* 3) 大于零，当前实例（this）大于obj对象
*
* Int32,Int16...,String,Decimal等数据类型都已经实现了IComparable接口
*/
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);
}
}
}

using System;
class Base
{
/*
* public 的可访问范围是所有类
* private 的可访问范围是当前类
* protected 的可访问范围是当前类及其子类
*/
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();
}
}

using System;
class SumToHundred
{
public static void Main()
{
int sum=0;
for(int i=1; i<=100; i++)
sum += i;
Console.WriteLine(sum);
}
}

using System;
class Account
{
private double balance = 0; //字段
public double Balance //属性
{
get { return balance; }
set { balance = value;}
}
/*=============================================================
* 我们可以通过修改get、set方法达到控制存取的目的。
* 例如：
*
* 1)只读属性
* public double Balance //属性
* {
* get { return balance; }
* set { }
* }
*
* 2)读写控制
* public double Balance
* {
* get
* {
* if(Console.ReadLine()=="1234")
* return balance;
* else
* return -9999999;
* }
* set { }
* }
* =============================================================
*/
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);
}
}