using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace 第三章
{
class Program
{
enum Mydate //日期枚举
{
Sun = 0,
Mon = 1,
Tue = 2,
Wed = 3,
Thi = 4,
Fri = 5,
Sat = 6
}
class C
{
private int _value;
public int Value
{
get { return _value; }
set { _value = value; }
}
}
static void Main(string[] args)
{
# region variable definition assignment
// definition of variable, assignment
int a;
string b;
int c = 0;
string d = "Duan Bin" ;
// Colleagues define multiple variables and assign values
int e, f, g;
string h, m, k;
string l = "Duan Bin", o = "Duan Bin", n = "Duan Bin";
string p;
/ /Assign a variable to a variable, which must be an assigned variable
b = l;
#endregion
#region variable domain
//for loop, the variable scope is only within the loop body
for (int i = 0; i <= 20; i++)
{
Console.WriteLine(i.ToString());
}
Console.ReadLine();
#endregion
#region variable Type
/*
*---------------------------
* Value type
* ------------------- ---
*/
int ls = 997;
byte test = 255;
Console.WriteLine("ls={0}", ls);
Console.WriteLine("test={0}", test);
Console.ReadLine() ;
//Force conversion
float fl = 3.14F;
double db = 3.14;
double dbTest = 32d;
fl = (float)db;
bool tr = true;
/*
* --------------- -------
* Reference type
* -----------------------
*/
int v1 = 0;
int v2 = v1;
v2 = 927;
C r1 = new C();
C r2 = r1;
//C r2 = new C();
r2.Value = 112;
Console.WriteLine("Value:{0},{1}", v1, v2);
Console.WriteLine("Refs:{0},{1}", r1.Value, r2.Value);
Console.ReadLine();
#endregion
#region Use of enumeration
int toDay = (int)DateTime.Now.DayOfWeek ; //Get the day of the week
switch (toDay)
{
case (int)Mydate.Sun:
{
Console.WriteLine("Today's Sunday");
break;
}
case (int)Mydate.Mon:
{
Console.WriteLine("Today's Monday" ");
break;
}
case (int)Mydate.Tue:
{
Console.WriteLine("Today's Tuesday");
break;
}
case (int)Mydate.Wed:
{
Console.WriteLine("Today's Wednesday");
break;
}
case (int)Mydate. Thi:
{
Console.WriteLine("Today is Thursday");
break;
}
case (int)Mydate.Fri:
{
Console.WriteLine("Today is Friday");
break;
}
case (int)Mydate.Sat:
{
Console.WriteLine("Today is Saturday");
break;
}
default:
{
break;
}
}
Console.ReadLine();
#endregion
#region data type conversion
double x = 19810927.8112;
int y = (int)x;//force explicit conversion
int zhuanB = 312;
double zhuanD = zhuanB; //Implicit conversion
Console.WriteLine(y);
Console.ReadLine();
//Boxing, value type is implicitly converted to reference type
int zhuanI = 2008;
object obj = zhuanI ;
Console.WriteLine("1 The value of zhuanI is {0}, and the boxed object is {1}", zhuanI, obj);//2008,2008
zhuanI = 927;
Console.WriteLine("2 The value of zhuanI is {0}, the boxed object is {1}", zhuanI, obj);//927,2008
//Unboxing, the reference type is cast to the value type
int zhuanX=(int)obj;
Console.WriteLine(" Unboxing: The object is: {0}, the value is {1}",obj,zhuanX);
Console.ReadLine();
#endregion
#region The use of constants
const double doublePI=3.1415926;//Constants must be initialized and assigned, and cannot be modified
Console.WriteLine(doublePI);
#endregion
}
}
}
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace 第三章
{
class Program
{
enum Mydate //日期枚举
{
Sun = 0,
Mon = 1,
Tue = 2,
Wed = 3,
Thi = 4,
Fri = 5,
Sat = 6
}
class C
{
private int _value;
public int Value
{
get { return _value; }
set { _value = value; }
}
}
static void Main(string[] args)
{
# region variable definition assignment
// definition of variable, assignment
int a;
string b;
int c = 0;
string d = "Duan Bin" ;
// Colleagues define multiple variables and assign values
int e, f, g;
string h, m, k;
string l = "Duan Bin", o = "Duan Bin", n = "Duan Bin";
string p;
/ /Assign a variable to a variable, which must be an assigned variable
b = l;
#endregion
#region variable domain
//for loop, the variable scope is only within the loop body
for (int i = 0; i <= 20; i++)
{
Console.WriteLine(i.ToString());
}
Console.ReadLine();
#endregion
#region variable Type
/*
*---------------------------
* Value type
* ------------------- ---
*/
int ls = 997;
byte test = 255;
Console.WriteLine("ls={0}", ls);
Console.WriteLine("test={0}", test);
Console.ReadLine() ;
//Force conversion
float fl = 3.14F;
double db = 3.14;
double dbTest = 32d;
fl = (float)db;
bool tr = true;
/*
* --------------- -------
* Reference type
* -----------------------
*/
int v1 = 0;
int v2 = v1;
v2 = 927;
C r1 = new C();
C r2 = r1;
//C r2 = new C();
r2.Value = 112;
Console.WriteLine("Value:{0},{1}", v1, v2);
Console.WriteLine("Refs:{0},{1}", r1.Value, r2.Value);
Console.ReadLine();
#endregion
#region Use of enumeration
int toDay = (int)DateTime.Now.DayOfWeek ; //Get the day of the week
switch (toDay)
{
case (int)Mydate.Sun:
{
Console.WriteLine("Today's Sunday");
break;
}
case (int)Mydate.Mon:
{
Console.WriteLine("Today's Monday" ");
break;
}
case (int)Mydate.Tue:
{
Console.WriteLine("Today's Tuesday");
break;
}
case (int)Mydate.Wed:
{
Console.WriteLine("Today's Wednesday");
break;
}
case (int)Mydate. Thi:
{
Console.WriteLine("Today is Thursday");
break;
}
case (int)Mydate.Fri:
{
Console.WriteLine("Today is Friday");
break;
}
case (int)Mydate.Sat:
{
Console.WriteLine("Today is Saturday");
break;
}
default:
{
break;
}
}
Console.ReadLine();
#endregion
#region data type conversion
double x = 19810927.8112;
int y = (int)x;//force explicit conversion
int zhuanB = 312;
double zhuanD = zhuanB; //Implicit conversion
Console.WriteLine(y);
Console.ReadLine();
//Boxing, value type is implicitly converted to reference type
int zhuanI = 2008;
object obj = zhuanI ;
Console.WriteLine("1 The value of zhuanI is {0}, and the boxed object is {1}", zhuanI, obj);//2008,2008
zhuanI = 927;
Console.WriteLine("2 The value of zhuanI is {0}, the boxed object is {1}", zhuanI, obj);//927,2008
//Unboxing, the reference type is cast to the value type
int zhuanX=(int)obj;
Console.WriteLine(" Unboxing: The object is: {0}, the value is {1}",obj,zhuanX);
Console.ReadLine();
#endregion
#region The use of constants
const double doublePI=3.1415926;//Constants must be initialized and assigned, and cannot be modified
Console.WriteLine(doublePI);
#endregion
}
}
}