The C# IS operator

will return true for tests of Interface implementation and class parentage

    interface IFuddy

    {

       string  test();

    }

    public class testBase: IFuddy

    {

        public string test()

        {

            return "hody";

        }

    }

    public class testA : testBase

    {

        public string atest()

        {

            return "hodydoe";

        }

    }

    public class testB : testBase

    {

        public string btest()

        {

            return "awaywego";

        }

    }

   private void retu(IFuddy f)

        {

            if (f is testA)

            {

                Response.Write((f as testA).atest());

            }

            if (f is testB)

            {

                Response.Write((f as testB).btest());

            }

            if (f is testBase)

            {

                Response.Write("f is testBase");

            }

            if (f is IFuddy)

            {

                Response.Write("f is IFuddy");

            }

        }

      protected void Button12_Click(object sender, EventArgs e)

        {

            testA t1 = new testA();

            testB t2 = new testB();

            retu(t1);

            retu(t2);

        }

Will write:

hodydoe
f is testBase
f is IFuddy
awaywego
f is testBase
f is IFuddy

ref with reference types

a vivid example:       

 private void changeRef(ref object o)

        {

            o = new GCNotificationStatus();

        }

        private void change(object o)

        {

            o = new GCNotificationStatus();

        }

        protected void Button14_Click(object sender, EventArgs e)

        {

            TaiwanCalendar t = new TaiwanCalendar();

            object test = t;

            change(test);

            Response.Write(test.GetType().FullName);   

            changeRef(ref test);

            Response.Write(test.GetType().FullName);

        }

cannot convert from 'ref blah' to 'ref object'

this doesnt compile:

private void changeRef(ref object o)

        {

            o = new GCNotificationStatus();

        }

        private void change(object o)

        {

            o = new GCNotificationStatus();

        }

        protected void Button14_Click(object sender, EventArgs e)

        {

            TaiwanCalendar t = new TaiwanCalendar();

            changeRef(ref t);

            change(t);

        }

the reason

Unable to load one or more of the requested types error

In your global.asax add a reference

using System.Reflection;

and handle ReflectionTypeLoadException

loop through the LoaderExceptions collection to find all missing references.

code for example

string appNamespace = null;

            try

            {

                // determine namespace of main assembly

                foreach (Assembly ass in AppDomain.CurrentDomain.GetAssemblies())

                {

                    foreach (Type type in ass.GetTypes())

                    {

                        if (type.IsSubclassOf(typeof(HttpApplication)))

                        {

                            appNamespace = type.Namespace;

                            break;

                        }

                    }

                    if (appNamespace != null)

                        break;

                }

            }

            catch(Exception ex)

            {

                StringBuilder sb = new StringBuilder();

                if (ex is ReflectionTypeLoadException)

                {

                    foreach (Exception exSub in ((ReflectionTypeLoadException)ex).LoaderExceptions)

                    {

                        sb.AppendLine(exSub.Message);

                        if (exSub is FileNotFoundException)

                        {

                            FileNotFoundException exFileNotFound = exSub as FileNotFoundException;

                            if (!string.IsNullOrEmpty(exFileNotFound.FusionLog))

                            {

                                sb.AppendLine(exFileNotFound.FusionLog);

                            }

                        }

                    }

                    try

                    {

                        using (StreamWriter outfile = new StreamWriter(Config.GetValue("Logger.ReferenceErrorLog", "referenceerror.log"), true))

                        {

                            outfile.Write(sb.ToString());

                        }

                    }

                    catch{}

                }

                else

                {

                   try

                   {

                    using (StreamWriter outfile = new StreamWriter(Config.GetValue("Logger.ReferenceErrorLog","referenceerror.log"),true))

                    {

                        outfile.Write(ex.Message);

                    }

                   }

                   catch { }

                    throw;

                }

            }

must declare a body because it is not marked abstract, extern, or partial

This error is not always giving the correct message

consider:

class Animal

    {

         Animal();

    }

  

this will raise the above error

but this :

     partial class Animal

    {

        partial Animal();

    }

    partial class Animal

    {

        Animal() { }

    }

wont help 

why? partial procedures need to return void

Why anonymous types are immutable in C#

Interesting article

Multiple classes in css and jquery

.blah1.blah2 are treated differently
in css this is "or" in jquery this is "and"

Why CSS matches selectors right to left

Good Answer

CSS precedence

what will happen here?

<head runat="server">
    <title>Untitled Page</title>
    <style type ="text/css"  >
        .testClass{color:red ; font-family:Calibri;background-color:Purple; font-size:xx-small  }
        #testID{color:blue ; font-size:x-large  }
        p {color:Green  ; background-color:Gray; font-size:small }
        html { font-size :xx-large  }  
    </style>
</head>
<body>
    <form id="form1" runat="server">
    <div>
    <p  class ="testClass"  id = "testID"   >
    dsfsdfdsf<br/>
    sdfsdf<br/>
    </p>
    </div>
    </form>
</body>
</html>

Style overrides ID that  overrides class that overrides element

c# interview questions (intermediate)

• is the LINQ Any operator a linear search?
• what patterns have you used in your code?
• if you needed to implement a process that had sub process A,B,C,D,E and B and D changed in detail in 5 situations - how would you model this?
• what is the Big O notation of a binary search?
• Can you describe how a hash table works?
• how can you add a compiler warning?
•        #warning
• Can you implement an interface that is using a base object with an implementation that is using a descendant class?
• how can you get the members of a class progromatically?
•         Type t = typeof(blah); MemberInfo[] m =  t.GetMembers();
• how can you alert a user of your class that a procedure is obsolete?
•          [Obsolete("hody doe")]
• can a private member ever be available to a different class without reflection?
•        Nested classes
• can you change the name of a rerefenced class to something else?
•        alias  - using msg = System.Windows.Forms.MessageBox; 
• var test = new { herby = "hello", age = 67f } what type is this?
• anonymous - system generated name
• what is the meaning of checked and uchecked keyword in c#?
• What type of objects are able to be queried by linq?
• IQueryable and IEnumerable
• when you have a readonly variable pointing to an object, can you change the value of the object?
• How would you reference a custom attribute added to a object?
• GetCustomAttributes, reflection
• Why are strings immutable in c#
• Which Interface would you implement for deep copying?
• ICloneable
• How can you add functionality to a sealed class?
• extension method
• How would encapsulate a reference type like a list as a member of a class to be read only?
• how to have a generic procedure make sure whatever is being passed implements an interface properly  
• void SwapIfGreater<T>(ref T lhs, ref T rhs) where T : System.IComparable<T>

• How to Explicitly Implement Members of Two Interfaces 
• interface IA
      {
           void hody();
      }
  
  
      interface IB
      {
           void hody();
      }
  
  
      class HodyDoe : IA, IB
      {
          void IA.hody()
          {
              Console.WriteLine("IA.hody"); 
          }
  
  
          void IB.hody()
          {
              Console.WriteLine("IB.hody"); 
          }
      }
     
      class Program
      {
          static void Main(string[] args)
          {
  
  
              HodyDoe h = new HodyDoe();
              (h as IA).hody();
              (h as IB).hody();
              Console.ReadLine(); 
  
  
          }
      }

Garbage collection is simulating a computer with an infinite amount of memory.

Good article

c# Interview Questions (Junior Developer)

• What is the difference between a value type and a reference type?
• When checking true false evaluations what is the difference between "&" and "&&"?
• Is  datetime a value type or a reference type?
• Is there any way to assign null to an int?
• How to get a distinct list from an array?
• What is boxing?
• What are generics and did you ever use them? What are the advantages of using generics?
• What is the difference between a hashtable and a dictionary?
• Can a dictionary have duplicate keys? Which structure can you use that allows duplicate keys?
• What does sealed mean and give an example of a c# system class that is sealed
• Can an abstract class have a constructor?
• Can a private member be virtual?
• can an abstract method be declared virtual?
• If you had to refactor code – what steps would you take?
• What are some advantages of a singleton over a static class?
• Can you inherit a static class?
• Can a static constructor have a parameter?
• Please explain garbage collection in .net
• Which interface do you need to implement to use
•                 “using” keyword
• IDisposable
•                 Foreach loops
• IEnumerable or IEnumerable<T>
•                 Custom sorting
• IComparable<T>
• Is there any way to find out the value of a private member of a class?
• Can a static procedure be recursive?
• An abstract class can have a public constructor? A private contructor?
• Whats the order of contructors with an inherited class? Static constructors?
• What is the difference between finalize and dispose?
• Are constructors inherited from base classes? 
• in c# can you change the access level of a derived overwritten procedure protected to public?
• if you have a derived class what difference is there between declaring "new" or "override" in a procedure?
• if a base class has a protected member, can the child class override to public?
• in c# - cannot change access modifiers when overriding 'protected' inherited member
• can you declare a protected class in a namespace
• no -Elements defined in a namespace cannot be explicitly declared as private, protected, or protected internal
• Can you declare a class to be private?
• Only with nested classes
• what is the default accessor for a class? for a class member?
• class - internal, member - private
• var something = 100.50F; what is the type of something?
• what is the difference between a const and a readonly value?
• what is the difference between typeof, GetType(), and is?
• what is the difference between ref and out?
• what is the difference between as and casting?
• what is the purpose of partial classes?
• if your argument is a reference type , does it make a difference if you use the ref keyword?
• what is the difference between Equals ,ReferenceEquals and "=="
• what is the value of y here:        int y = x ?? -1;
• How would you remove duplicate entries in an array?
• what is the value of 5/2 in c#?
• can you share namespaces over projects?
• Does array.Clone() create a deep or shallow copy?
• does this compile?
•     {
•                 string s = "gdfgd";
•             }
•             {
•                 string s = "gdfgd";
•             }
•         }

Naming Issues in .net

If you name a class in a namespace the same name as a project , you are inviting trouble.

for e.g. , references will now be confused
if you have a project called test and you add a class called test and you have a service reference called document, for example,

this will now not compile

        private test.Document.blah[] blahs;

Advantages of Singleton over static class

• no need to declare static in procedures
• ability to use inheritance, implement interfaces
• ability to pass class as an argument

Difference between hashtable and dictionary

besides the usual answer with the need to cast or boxing -

• Hashtable returns null with a nonexistent key  
• collision handling

attribute selectors

Great article on attribute selectors

Sample Javascript Interview Questions

//1

//what value will show with the alert?

test = "herby";

{

    var test = "not herby";

}

alert(test);

//1

//2

//what value will show with the alerts?

//how would you write this differently

function triple(x)

{

i= 3;

return x * i;

}

var i =2;

alert(triple(i)) ;

alert(i);

//2

//3

//will this run? why or why not?

var o = new Object;

o.totriple = triple;

with(o)

{

alert(totriple(5));

}

//

//4

//what are the results and why

alert("1"==true);

alert("1"===true);

//

//5

//what value will show with the alert?

//this applies to other languages also

var x = 1;

var y = x++;

alert(y);

//5

//6

//will the alert run?

//bonus - what is this called?

if(x==0 && y ==0);

alert("can this be?");

//

//7

//what are the results here?

alert("1" + 2);

alert(1 + "2");

alert(1 + 2 + " hello");

alert(" hello" + 1 + 2);

alert("19" < "2");

//7

//8

//question - can you make javascript mimic c#'s startwith function for strings?

String.prototype.startsWith = function(s){ return (this.substr(0, s.length) == s)  }

var test ="test";

alert(test.startsWith("te"));

alert(test.startsWith("ete")); 

//8

//9

//what value is num?  

var num = 34/0;

alert(num);

//9

//10

//will the value be true and why?

//is there any way of doing this?

var num2 = 0/0;

var num3 = 0/0;

alert(num2==num3);

//10

//11

//what will show?

alert("n\n\\n");

//11

//12

//is the if statement true

var num4;

if(num4===null)

  alert("here");

//12

//13
var t   = 0||67;alert(t); 
//13

Science- Fiction & scrum

I was thinking , lets adapt a famous science-fiction trope (cliche?) and see how it would fit scrum.

tell the scrum master that scrum is an impediment...
and watch him explode.

A first chance exception of type

means a handled exception