第一节 赋值和常用数据类型。向控制台输出HelloWorld
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//案例1:向控制台输出 HelloWorld using System ; //导入命名空间 public class HelloWorld //声明一个类,类名:HelloWorld { public static void Main() //声明主函数 { Console.WriteLine("HelloWorld !");//用于向控制台输出:“HelloWorld !” } }
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//案例2 :赋值 //变量的声明 //创建整型的变量,=赋值运算符 int i = 10; //先声明,后赋值 int j; j = 20; Console.WriteLine(i); Console.WriteLine(j); Console.WriteLine("重新赋值后:"); //重复赋值 i = 100; j = 200; Console.WriteLine(i); Console.WriteLine(j); Console.ReadKey();
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//案例三 :数据类型 //数据类型 标识符=值 //整型 int i = 10; //单精度浮点型 float f = 3.4F; //字节型 byte b = 255; //短整型 short sh = 3275; //长整型 long l = 545545454545455; //布尔型 bool bf = false; bool bt = true; //字符串 string str = "你好!谢谢"; //双精度浮点型 double d = 3.14156906; // 十进制小数 decimal dec = 3.14M; //字符型 char c = 'j'; Console.WriteLine("整型:" + i); Console.WriteLine("单精度浮点型:" + f); Console.WriteLine("字节型:" + b); Console.WriteLine("短整型:" + sh); Console.WriteLine("长整型:" + l); Console.WriteLine("布尔型;" + bf+","+bt); Console.WriteLine("字符串:" + str); Console.WriteLine("双精度浮点型:" + d); Console.WriteLine("十进制小数:" + dec); Console.WriteLine("字符型:" + c);
变量命名规范:
开头:字母或下划线
不能使用关键字