using System;

namespace _009_关系运算符和布尔类型
{
    class Program
    {
        static void Main(string[] args)
        {
            //    bool a = true;//是的  真的  满足条件  1
            //    bool b = false;//不是  假的  不满足条件  0
            //    Console.WriteLine(a);//Ctrl+D 快速复制一行代码
            //    Console.WriteLine(b);

            bool a = 45 == 67;
            bool b = 45 < 67;
            bool c = 45 <= 67;
            bool d = 45 > 67;
            bool e = 45 >= 67;
            bool f = 45 != 67;

            Console.WriteLine(a);//False
            Console.WriteLine(b);//True
            Console.WriteLine(c);//True
            Console.WriteLine(d);//False
            Console.WriteLine(e);//False
            Console.WriteLine(f);//True
        }
    }
}

using System;

namespace _008_自增自减运算符
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 5;
            //a++;//a=a+1;
            //++a;//
            //int b = a++;//a++先赋值再自增    ++a先自增再赋值
            //int b = ++a;
            //Console.WriteLine(a + ":" + b);

            Console.WriteLine(a++);
            Console.WriteLine(a);
        }
    }
}

using System;

namespace _007_数学运算符
{
    class Program
    {
        static void Main(string[] args)
        {
            //int num = 39;
            //int ge = num % 10;
            //int shi = num / 10;
            //Console.WriteLine("个位是{0}，十位数是{1}", ge, shi);

            //int a = 0;
            //a + 1;
            //Console.WriteLine(a);

            //int a = 0;
            //a = a + 1;
            //Console.WriteLine(a);//1

            int a = 0;
            a += 10;//a=a+10;
            Console.WriteLine(a);
            a -= 5;//5;
            Console.WriteLine(a);
            a *= 3;//15
            Console.WriteLine(a);
            a /= 6;//2
            Console.WriteLine(a);
            a %= 2;//0
            Console.WriteLine(a);
        }
    }
}

c# 代码会被编译成 exe 和 dll 程序集，而不是直接就被编译成二进制文件。当程序集运行的时候 会被及时的编译成二进制文件 供电脑执行。

为什么需要这多一步呢？

老师说程序集是跑在 .net框架环境里面。多这一步是为了方便开发者能够使用到 net框架自带的一些东东。。。

using System;

namespace _007_数学运算符
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 23 + 23;
            int b = 2 - 10;
            int c = 4 * 23;
            int d = 45 / 10;
            int e = 45 % 10;

            double f = 45 / 10.0;

            Console.WriteLine(a);
            Console.WriteLine(b);
            Console.WriteLine(c);
            Console.WriteLine(d);
            Console.WriteLine(e);
            Console.WriteLine(f);
        }
    }
}

using System;

namespace _006_变量研究
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 23, b = 45;
            // 23+45=68
            //Console.WriteLine(a + "+" + b + "=" + (a + b));
            Console.WriteLine("{0}+{1}={2}", a, b, a + b);//0 1 2

            Console.WriteLine("两个数字相加{0}+{0}={2}",34,123,4);

            //Console.WriteLine("两个数字相加{0}+{0}={3}",34,123,4);//不存在{3}报错
        }
    }
}

using System;

namespace _006_变量研究
{
    class Program
    {
        static void Main(string[] args)
        {
            //int class namespace string void

            int age;
            int myAge;
            int xiaomingAge;
            double enemyHp;
            double PI;
            int HP;
            int MP;
        }
    }
}

变量驼峰命名；

方法和类名Pascal命名。

using System;

namespace _006_变量研究
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 5, b = 10;

            //a = b;
            //b = a;

            //int temp = a;
            //a = b;
            //b = temp;

            a = a + b;
            b = a - b;
            a = a - b;

            Console.WriteLine(a);
            Console.WriteLine(b);
        }
    }
}

减法交换变量：

            a = a - b;//5-10=-5
            b = b + a;//10+(-5)=5
            a = b - a;//5-(-5)=10

using System;

namespace _005_练习题
{
    class Program
    {
        static void Main(string[] args)
        {
            //int a = Convert.ToInt32(Console.ReadLine());
            //int b = Convert.ToInt32(Console.ReadLine());
            //int c = a + b;
            //Console.WriteLine(c);

            int a = Convert.ToInt32(Console.ReadLine());
            int b = Convert.ToInt32(Console.ReadLine());
            int c = (a + b) / 2;
            Console.WriteLine(c);
        }
    }
}

using System;

namespace _004_字符类型
{
    class Program
    {
        static void Main(string[] args)
        {
            //怎么读取数据 输入数据
            //string str = Console.ReadLine(); // "12" 12
            //Console.WriteLine(str + "-");

            //1、类型一致  2、右边的值所需要的容器大小 小于等于左边的容器
            //int a = Console.ReadLine();

            string str = Console.ReadLine();// "12" 12
            int strInt = Convert.ToInt32(str);// "12" 12   "df"

            int a = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine(strInt + "-" + a);
        }
    }
}

using System;

namespace _004_字符类型
{
    class Program
    {
        static void Main(string[] args)
        {
            //char a = 'c';
            //int b = a;
            //Console.WriteLine(a);
            //Console.WriteLine(b);//99

            //97 a
            //int a = 97;
            //char b = (char)a;//强制类型转换 强塞
            //Console.WriteLine(a);
            //Console.WriteLine(b);

            //char a = '1';
            //int b = a;
            //Console.WriteLine(a);
            //Console.WriteLine(b);

            //char a = '\n';
            //char b = '\\';
            //char c = '\"';
            //char d = '\t';
            //char e = '\'';

            //Console.WriteLine("c:\\a\\b\\c");
            //Console.WriteLine(@"c:\a\b\c");
            //Console.WriteLine(@"c:\\a\\b\\c");

            //string str = @"www.sikiedu.com\nsiki";
            //            string str = @"www.sikiedu.com ""
            //abc
            //123
            //456789";
            //            Console.WriteLine(str);

            string str = "123" + "456";
            string str2 = str + "www";
            Console.WriteLine("www" + 123);
        }
    }
}

using System;

namespace _004_字符类型
{
    class Program
    {
        static void Main(string[] args)
        {
            //char a = 'c';
            //int b = a;
            //Console.WriteLine(a);
            //Console.WriteLine(b);//99

            //97 a
            int a = 97;
            char b = (char)a;//强制类型转换 强塞
            Console.WriteLine(a);
            Console.WriteLine(b);
        }
    }
}

using System;

namespace _003_变量
{
    class Program
    {
        static void Main(string[] args)
        {
            int a = 3, b = 8;
            Console.WriteLine(a + b);//11
            Console.WriteLine("a + b");//a + b
            Console.WriteLine(a + "+" + b);//3+8
            Console.WriteLine("a+b" + a + b);//a+b38
            Console.WriteLine("a+b" + (a + b));//a+b11
        }
    }
}

using System;

namespace _003_变量
{
    class Program
    {
        static void Main(string[] args)
        {
            int total;

            //赋值
            total = 4;

            //int a;
            //a = 1;
            //int b = 1;

            int a = 1;
            a = 3 + 7 - 2;
            int b = 3;
            b = b + 1;

            Console.WriteLine(a);
            Console.WriteLine(b);

            int c;
            c = 10;//初始化
            c = 11;
            Console.WriteLine(c);

            //female male
            char sex = 'f';
            sex = 'm';
        }
    }
}

using System;

namespace _003_变量
{
    class Program
    {
        static void Main(string[] args)
        {
            //创建变量
            //创建了一个数据的容器，容器的名字叫做age，容器的类型是int
            //声明了一个变量，变量的名字是age
            int age; //int变量类型 age变量名
            //往容器里面放东西 赋值
            age = 10;

            double age2;

            char age3;

            double height;

            char sex;

            int count;

            double ave;

            int total;
            
            double temperature;
        }
    }
}

C#编译

代码 -> 程序集（exe dll）

程序集在运行的时候会编译成机器指令（JIT 及时编译）

using System;

namespace _002_练习
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("*");
            Console.WriteLine("**");
            Console.WriteLine("***");
            Console.WriteLine("****");
            Console.WriteLine("*");
            Console.WriteLine("*");
            Console.WriteLine("*");
        }
    }
}

2

using System;

namespace _002_练习
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("   *");
            Console.WriteLine("  ***");
            Console.WriteLine(" *****");
            Console.WriteLine("*******");
            Console.WriteLine("   *");
            Console.WriteLine("   *");
            Console.WriteLine("   *");
        }
    }
}

3

using System;

namespace _002_练习
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("\\\"");
        }
    }
}

4

using System;

namespace _002_练习
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("SiKi说:\"what is\\n\"");
        }
    }
}

using System; //注释：引入命名空间

namespace _001_开始
{
    //这个是Program类
    class Program
    {
        //这个是Main方法
        static void Main(string[] args)
        {
            //ctrl + k ctrl + c
            //Console.WriteLine("Hello World!1");//这个是输出语句
            /*
             sdf
            sdf   sdf
            sdf
             */
            //Console.WriteLine("Hello World!2");

            //Console.WriteLine("Hello World 你好，世界3");

            //Console.Write("Hello,World!");
            //Console.Write("www.sikiedu.com");
            Console.WriteLine("Hello ");
            Console.WriteLine("World!");

            Console.WriteLine("He\tllo \nWorld!\\");
        }
    }
}

（1）注释：

单行注释 //

多行注释 /* zhushi */

注释快捷键：ctrl+k ctrl+c

取消注释快捷键：ctrl+k ctrl+u

（2）语句结束加上 ;

（3）代码块 { }

（4）顺序执行

（5）Write 输出后不换行，WriteLine 输出后换行。