C# 笔记之基本语法

C#是一种现代的、通用的编程语言，由微软公司开发和推广。它于2000年发布，是一种结构化、面向对象和组件化的语言，旨在为Windows操作系统和Microsoft .NET框架提供强大的支持。可用于开发各种类型的应用程序。它在企业和开源社区中都非常受欢迎，并且具有广泛的支持和资源。

标准输入输出:

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("hello world");
            string Str = Console.ReadLine();
            Console.WriteLine(Str);
        }
    }
}

常用变量类型：

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            byte s_byte = 254;
            sbyte s_sbyte = 126;
            short s_short = 32766;
            int s_int = 2147483645;
            double s_double = 3.1415926;
            decimal d_decimal = 5000m;
            string s_string = "hello lyshark";
        }
    }
}

if语句:

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            const int x = 100;
            const int y = 200;
            int source = 0;
            Console.WriteLine("请输入一个数:");
            source = int.Parse(Console.ReadLine());
            if (source == 0)
            {
                Console.WriteLine("你没有输入任何数.");
            }
            else if (source > x && source < y)
            {
                Console.WriteLine("符合规范");
            }
            Console.ReadKey();
        }
    }
}

switch

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("输入一个整数: ");
            int score = Convert.ToInt32(Console.ReadLine());
            switch (score / 10)
            {
                case 10:
                case 9:
                    Console.WriteLine("A");break;
                case 8:
                case 7:
                    Console.WriteLine("B");break;

                default:
                    Console.WriteLine("none");break;
            }
            Console.ReadKey();
        }
    }
}

while-dowhile

using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] MyArray = new int[10] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };

            int index = 0;
            while (index < 10)
            {
                Console.WriteLine("数组中的值: {0}", MyArray[index]);
                index++;
            }

            index = 0;
            do
            {
                Console.Write("{0} ", MyArray[index]);
                index++;
            } while (index < 10);

            Console.ReadKey();
        }
    }
}

for

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] MyArray = new int[10] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };

            for (int index = 0; index < MyArray.Length; index++)
            {
                Console.WriteLine("下标:{0} --> 数据: {1}", index, MyArray[index]);
            }

            ArrayList alt = new ArrayList();

            alt.Add("你好");
            alt.Add("世界");
            foreach (string Str in alt)
            {
                Console.WriteLine("输出: {0}", Str);
            }

            Console.ReadKey();
        }
    }
}

break

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int x = 0; x < 5; x++)
            {
                for(int y=0; y<10 ;y++)
                {
                    if (y == 3)
                        break;
                    Console.WriteLine("输出: {0}",y);
                }
            }
            Console.ReadKey();
        }
    }
}

goto

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] MyStr = new string[3];

            MyStr[0] = "hello";
            MyStr[1] = "world";
            MyStr[2] = "lyshark";

            for (int x = 0; x < MyStr.Length; x++)
            {
                if(MyStr[x].Equals("lyshark"))
                {
                    goto Is_Found;
                }
            }
        Is_Found:
            Console.Write("查找到成员");
            Console.ReadKey();
        }
    }
}

判断闰年案例:

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            try
            {
                Console.Write("输入年份: ");
                int year = Convert.ToInt32(Console.ReadLine());
                Console.Write("输入月份: ");
                int month = Convert.ToInt32(Console.ReadLine());
                if (month >= 1 && month <= 12)
                {
                    int day = 0;
                    switch (month)
                    {
                        case 1:
                        case 3:
                        case 5:
                        case 7:
                        case 8:
                        case 10:
                        case 12: day = 31; break;
                        case 2:
                            if ((year % 400 == 0) || (year % 4 == 0 && year % 100 != 0))
                                day = 29;
                            else
                                day = 28;
                            break;
                        default: day = 30; break;
                    }
                    Console.WriteLine("{0}年{1}月有{2}天", year, month, day);
                }
            }
            catch
            {
                Console.WriteLine("异常了");
            }
            Console.ReadKey();
        }
    }
}

99口诀表

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            for (int x = 1; x <= 9; x++)
            {
                for (int y = 1; y <= x; y++)
                {
                    Console.Write("{0} * {1} = {2} \t", y, x, x * y);
                }
                Console.WriteLine();
            }
            Console.ReadKey();
        }
    }
}

随机数产生:

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Random rand = new Random();

            for (int x = 0; x < 100; x++)
            {
                int Num = rand.Next(1, 1024);
                Console.WriteLine("随机数: {0}", Num);
            }
            Console.ReadKey();
        }
    }
}

枚举类型:

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections;

namespace ConsoleApplication1
{
    public enum QQState
    {
        OnLine = 1,
        OffLine,
        Leave,
        Busy,
        QMe
    }

    class Program
    {
        static void Main(string[] args)
        {
            QQState state = QQState.OnLine;
            // 将state强转为整数
            int num = (int)state;
            Console.WriteLine(num);

            // 将整数强转为枚举类型
            int num1 = 2;
            QQState x = (QQState)num1;
            Console.WriteLine("状态: {0}",x);

            // 输入一个号兵输出对应状态
            string input = Console.ReadLine();
            switch(input)
            {
                case "1":
                    QQState s1 = (QQState)Enum.Parse(typeof(QQState), input);
                    Console.WriteLine("状态: {0}", s1);
                    break;
            }
            Console.ReadKey();
        }
    }
}

定义结构数据:

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

namespace ConsoleApplication1
{
    class Program
    {
        // 定义结构数据
        public struct Person
        {
            public double width;
            public double height;

            // 结构体支持构造函数
            public Person(double x, double y)
            {
                width = x;
                height = y;
            }
        }

        static void Main(string[] args)
        {
            Person per;

            per.width = 100;
            per.height = 200;
            Console.WriteLine("x = {0} y = {1}", per.width, per.height);

            Person ptr = new Person(10, 20);
            Console.WriteLine("x = {0} y = {1}", ptr.width, ptr.height);

            Console.ReadKey();
        }
    }
}