变量，常量
int a,b,c;
a =12;
b =3;
c=a +b;
Console.WriteLine(c);
// 常量
string e = "你好";
Console.WriteLine(e);
const int d=7;
Console.WriteLine(d+c);
/* Console.Write("输入");
string s = Console.ReadLine(); //将界面输入的字符接受赋值s
Console.WriteLine("输入的内容是"+s);*/
/* string a, b;
a = "1";
b = "12";
a = a + b;
Console.WriteLine(a);*/
运算符(注意优先级)
Console.WriteLine("请输入变量a的值");
string a = Console.ReadLine();
Console.WriteLine("请输入变量b的值");
string b= Console.ReadLine();
Console.WriteLine("a*b的值为：");
Double a1 = Double.Parse(a);
Double b1 = Convert.ToDouble(b); //类型转换
Double c = a1 * b1;
Console.WriteLine(c);*/
/* Console.Write("a的值：");
int a = int.Parse(Console .ReadLine ()); //类型转换
Console.Write("b的值：");
int b = int.Parse(Console .ReadLine ());
int c = a + b;
Console.WriteLine("a+b:"+c );
int d = ++a;
//int c =a++------int c=a,a=a+1;a++(先赋值后运算);++a(先运算后赋值)
a*=b—————a=a*b;a*=b-1—————a=a*(b-1)
bool o = a > b||a*b<=c+d;
Console.WriteLine(o);*/
/* Console.Write("a的值：");
int a = int.Parse(Console .ReadLine ());
int e = 4;
e +=--e;
Console.WriteLine(e);
bool i=!(a +e<=a *e&&a >e );
Console.Write(i);*/
Console.Write("输入数字：");
int a = int.Parse(Console.ReadLine ());
string s= a> 12?"下午 "+ ( a-12 ):"上午"+a; //条件?___:___
Console.Write(s);
Console.Write("a的值：");
double a = double.Parse(Console.ReadLine());
Console.Write("b的值：");
double b = double.Parse(Console.ReadLine());
double c = a + b;
Console.WriteLine("a+b的值：" + c);
c = a * b;
Console.WriteLine("a*b的值：" + c);
c = a - b;
Console.WriteLine("a-b的值：" + c);
c = a / b;
Console.WriteLine("a/b的值：" + c);
double d = ++a;
double e = ++b;
bool l =!(a > b&&d>e);
Console.WriteLine(l);}*/
Console.Write("a的值：");
int a = int.Parse(Console.ReadLine());
Console.Write("b的值：");
int b = int.Parse(Console.ReadLine());
int c = ++a;
int d = ++b;
int e = c + d;
Console.WriteLine("c+d:"+e);
bool l = d + e < a * b;
Console.WriteLine(l);