using System;
using System.Collections.Generic;
using System.Text;
using wr = System.Console;
namespace ConsoleApplication1
{
class Program
{
public static void Main(string[] args)
{
//Console.WriteLine(args[0]);
//this.nonstatic(); //no non static methods are accessable.
//nstring();
//extra();
//stconstr();
// nstuct();
////mypass.run();
//myparam.run();
//myprop3.Run();
//myindex.run();
//attclass.run();
// intclass2.run();
//Pr1.run();
wr.ReadLine();
}
public static void temp()
{ }
//private variables that are not marked as static cannot be utilised by a static method.
public void nonstatic() { } //It is invalid for one static method to directly
//call a non-static method or property without first instantiating an object.
public static void nmystatic1()
{
new mystatic1();
new mystatic1();
wr.WriteLine(mystatic1.varstat1);
}
public static void stconstr()
{
mystatic2 ms = new mystatic2();
wr.WriteLine("hostname : {0} and ipaddres : {1}", mystatic2.hostname, mystatic2.ipaddr);
}
public static void nstring()
{
Emp e = new CEmp();
CEmp x = (CEmp)e; //write usage
// x = (CEmp) new Emp(); //wrong usage
// x.Cstring();
}
public static void extra()
{
Emp e = new Emp();
wr.WriteLine(e.GetType());
wr.WriteLine(e.GetHashCode());
wr.WriteLine(e.ToString());
}
public static void nstuct()
{
mystruct1 st1;
st1.e = 1;
st1.r = 2;
st1.w = 3;
mystruct1 st2 = new mystruct1(); //it will initialize all the int types with 0
Console.WriteLine("{0} {1}", st2.e, st1);
}
}
}
class Emp : System.Object
{
public Emp() { }
}
class CEmp : Emp
{
public CEmp()
{ Cstring(); }
public void Cstring()
{
string[] str = { "sfsf", "sdf", "sdfsf" };
//string[] str2 = { "sfsf", 2, 3};
string[] str1 = new string[1];
int[] arr1;
arr1 = new int[10];
arr1 = new int[20];
wr.WriteLine(arr1[5]);
int[,] arr2;
arr2 = new int[2, 3]; //Multidimensional arrays:
wr.WriteLine(arr2[0, 1]);
int[][] arr3; //Array-of-arrays (jagged)
arr3 = new int[4][];
for (int i = 0; i <>
arr3[i] = new int[i + 1];
string str3 = @"c:\Docs\Source\a.txt"; //@"c:\Docs\Source\a.txt" // rather than "c:\\Docs\\Source\\a.txt"
wr.WriteLine(str3 + " " + str3[2]);
str3 = @"sdfsfsf";
str1[0] = "hello";
Console.WriteLine(str1[0]);
// Console.ReadLine();
//@"c:\Docs\Source\a.txt" // rather than "c:\\Docs\\Source\\a.txt"
//ConsoleApplication1.Program.Main(str1); //correct
}
}
// private class mystatic { } // no access mofifiers in class
class mystatic1
{
public mystatic1()
{ varstat1++; }
public static int varstat1;
}
class mystatic2
{
/*//A static constructor is used to initialise the static state of a class when
//it is first used. access modifiers private or publiv arent allowed on static
* constructors.. A static constructor therefore has no facility to add parameters.
* It is also not possible to include a static destructor.
//static constructors are used to initialize static fields, readonly or otherwise.
//we are not writing any access modifier for static constructor as they are by definition, always public.
* you can have only one static constructor and it cant access instance members including this pointer.
* you can provide a non static constructor with the same signature as static constructor and if u
* do this then both constructors will get called before the first instance of a class
* is created with the static version called first.
*/
static mystatic2()
{
System.Net.IPAddress ipad = System.Net.Dns.Resolve(hostname).AddressList[0];
ipaddr = ipad.ToString();
}
public const string hostname = @"www.google.com";
public static readonly string ipaddr;
}
sealed class mysealed
{
public mysealed(int x, int y)
{
this.x = x;
this.y = y;
}
int x, y;
}
/*like a class, a stuct dont incur the overhead associated with reference objects.
client doesnt have to instantiate the stuct(new keyword). its a value type so is allocated
once its declared.
*/
public struct mystruct1 //doesnt have a default constructor
{
public int r, w, e;
public override string ToString()
{
return w.ToString();
}
}
/* u sue struct when data is very small or it contais few or no methods to access or modify
* constained data
* a class is an encapsulation of data and the methods that work on that data. structs can
* be viewed as simple data.
*/
public struct mystruct2
{
//public mystruct2() //parameterless constructor of a structure is not allowed.
public mystruct2(int r, int w, int e)
{
this.e = e;
this.w = w;
this.r = r;
}
public int r, w, e;
}
//passing reference type by reference is same as passing by value.
class mypass
{
public mypass()
{
a = 10;
b = 20;
c = 30;
}
int a;
int b;
int c;
public void valpass(int a, int b, int c)
{
a = 5;
b = 10;
c = 15;
wr.WriteLine("val pass : {0} {1} {2}", a, b, c);
}
public void refpass(ref int a, ref int b, ref int c)
{
a = this.a;
b = this.b;
c = this.c;
wr.WriteLine("ref pass : {0} {1} {2}", a, b, c);
}
public void outpass(out int a, out int b, out int c) //out parameters must be modified in the called method.
{
// c = a; can not use out parameter before modifying
a = this.a + 1;
b = this.b + 1;
c = this.c + 1;
wr.WriteLine("out pass : {0} {1} {2}", a, b, c);
}
public void objpass(out mypass m)
{
// int x = m.a; can not use m before assigning it to another object
m = new mypass(); //now u can use it.
}
//passing reference type by reference is same as passing by value.
public void objpass2(ref mypass m1, mypass m2)
{
//will work same
m1.a = m1.a + 1;
m2.a = m2.a + 1;
//will work diff
m1 = new mypass(); //same ref is passed so value will get changed in the root ref
m2 = new mypass(); //copy of the reference is passed so root will remain unchanged.
}
public static void run()
{
int a = 1, b = 2, c = 5; // for ref and val parameter initialization is necessary
int d = 1, e = 2, f = 5;
int g = 6, h, i; // parameter may or may not be initialized for out.
mypass m = new mypass();
wr.WriteLine("val pass : {0} {1} {2}", a, b, c);
m.valpass(a, b, c);
wr.WriteLine("ref pass : {0} {1} {2}", d, e, f);
m.refpass(ref d, ref e, ref f);
//wr.WriteLine("ref pass : {0} {1} {2}", g, h, i);
m.outpass(out g, out h, out i);
}
}
/*method overload
* access modifier and return type doesnt count
* ref and out are enough
* you can use either ref or out but not both,
constructor overloading -
* its like public func_constructor(int a) : this()
* where this is default constructor but no longer valid after the explicit use.
* we can also call other constructor from one constructor like this
* public func_constructor(int a) : this("hello")
* overloaded methos is considered an overloaded even if other overloaded versions of the
* funcitons exist in the base class rather than current class.
*/
class myparam
{
static void param1(params int[] a)
{
foreach (int b in a)
{
wr.WriteLine(b);
}
//or
/* for (int i = 0; i <>
{
wr.WriteLine(a[i]);
}*/
/* public void func(params object[] a)
* it can take ny number of parameters of ny type
*/
}
public static void run()
{
param1(1, 2);
param1(5, 6, 7);
}
}
/*method overriding - type of polymorphism
*in the derived method, wherther we are using 'new' of not, it will be by default to all
* the methods with diff name diff arguments or same name same arguments.
* in the upcast the base reference will always point to the base method.
* it happpens due to early binding which is binding of method at compile time which is
* C# looks at the call and determines the address in memory needed to jump to when call
* is made and in case memory location of the method.
* late binding means that the compiler doesnt select the method to excute until runtme.
* for this we must use virtual and override keyword.
* polymorphic class - using virtual and override
* non polymorphic class - using new.
* the point is in virtual function table
* a constructor cant be virtual.
* new virtual is also possible - only virtual means new by default.
*/
class myprop1
{
int salary = -1;
public virtual int Salary
{
// get; allowed only for abstract or extern class
get
{ return salary; }
set { }
}
}
/* only getter - readonly property..only setter - write only property
* both setter n getter - read-write property
* cant be used as parameter to methods.
* static properties doesnt not have virtual abstract or override keywords
* members defined as abstract within an abstract class must be implemented by any derived class
*
*/
class myprop2 : myprop1
{
int salary = 10;
public override int Salary
{
get
{
return salary + 5;
}
set
{
salary = value;
}
}
}
class myprop3 : myprop1
{
int salary = 20;
public override int Salary
{
get
{
return salary + 1;
}
set
{
salary = value;
}
}
public static void Run()
{
myprop1[] m1 = new myprop1[2];
m1[0] = new myprop2();
m1[1] = new myprop3();
wr.WriteLine("1st {0} 2nd {1}", m1[0].Salary, m1[1].Salary);
m1[0].Salary = 50;
m1[1].Salary = 100;
wr.WriteLine("1st {0} 2nd {1}", m1[0].Salary, m1[1].Salary);
}
}
class myindex
{
System.Collections.ArrayList a = new System.Collections.ArrayList();
public object this[int i]
{
get
{
if (i > -1 && i <>
return a[i];
else
return "error";
}
set
{
if (i <>
a[i] = value;
else if (i == a.Count)
a.Add(value);
}
}
public static void run()
{
myindex m = new myindex();
m[0] = "asfd";
m[1] = 2;
wr.WriteLine(m[0] + " " + m[1]);
wr.WriteLine(typeof(myindex));
//wr.WriteLine(m[0],m[1]); //error
}
}
public enum myenum
{
monday,
tuesday,
wednesday,
thursday,
friday,
saturday,
sunday
}
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Field | AttributeTargets.Method, AllowMultiple = true, Inherited = true)]
class myattribAttribute : Attribute
{
public myattribAttribute(string name)
{
this.Name = name;
}
myenum day;
public myenum Day
{
get { return day; }
set { day = value; }
}
string name;
public string Name
{
get { return name; }
set { name = value; }
}
}
[myattrib("DayThursday", Day = myenum.thursday)]
class attclass
{
[myattrib("DayWednesday", Day = myenum.wednesday)]
public void Method()
{
}
public void method2() { }
[myattrib("DayFiday", Day = myenum.friday)]
public int field;
public int field1;
public static void run()
{
Type type = Type.GetType("attclass");
foreach (Attribute att in type.GetCustomAttributes(true))
{
if (att is myattribAttribute)
{
myattribAttribute myat = att as myattribAttribute;
wr.WriteLine("{0} {1}", myat.Name, myat.Day);
}
}
foreach (System.Reflection.MemberInfo mi in type.GetMethods())
{
foreach (Attribute att in mi.GetCustomAttributes(true))
if (att is myattribAttribute)
wr.WriteLine(mi.Name);
else wr.WriteLine("not {0}", mi.Name);
}
foreach (System.Reflection.FieldInfo fi in type.GetFields())
{
foreach (Attribute att in fi.GetCustomAttributes(true))
{
if (att is myattribAttribute)
{
myattribAttribute myat = att as myattribAttribute;
wr.WriteLine(fi.Name);
wr.WriteLine("{0} {1}", myat.Name, myat.Day);
}
}
}
}
}
class intclass1
{
void printf1()
{
wr.WriteLine("print int class1");
}
}
interface inf1
{
int count();
void printf1();
}
interface inf2
{
void printf2();
}
interface inf3 : inf1, inf2
{ }
interface inf4
{
int count();
}
class intclass2 : intclass1, inf3, inf4
{
public void printf2()
{
wr.WriteLine("intf3->intf2");
}
public void printf1() //new keyword is by default
{
wr.WriteLine("intf3->intf1");
}
int inf1.count() //inf1 is used instead inf3
{
return 2;
}
int inf4.count()
{
return 3;
}
public static void run()
{
intclass2 infc2 = new intclass2();
((inf3)infc2).printf1();
// infc2.count-----name hidding
}
}
class myclock
{
public delegate void del(Timeargs t1);
public event del ev;
int sec, hour, min;
public void onsecchange(Timeargs ti)
{
if (ev != null)
ev(ti);
}
public void run()
{
while (true)
{
System.Threading.Thread.Sleep(1000);
DateTime dt = DateTime.Now;
if (dt.Second != sec)
{
Timeargs tm = new Timeargs(dt.Hour, dt.Minute, dt.Second);
this.sec = dt.Second;
this.hour = dt.Hour;
this.min = dt.Minute;
onsecchange(tm);
}
}
}
}
class logi
{
public void subscribe(myclock mc)
{
mc.ev += new myclock.del(logger);
}
public void logger(Timeargs tm)
{
Console.Write("\r{2}:{0}:{1}", tm.min, tm.sec, tm.hour);
}
}
class Timeargs
{
public Timeargs(int hour, int min, int sec)
{
this.hour = hour;
this.sec = sec;
this.min = min;
}
public readonly int hour, min, sec;
}
class Pr1
{
public static void run()
{
string[] a = new string[5];
myclock mc = new myclock();
logi lg = new logi();
lg.subscribe(mc);
mc.run();
// Console.ReadLine();
}
private static void func1(string message)
{
Console.WriteLine(message);
}
}
No comments:
Post a Comment