Technical Interview Questions » C# Interview Questions

Is it possible to restrict the scope of a field/method of a class to the classes in the same namespace?

admin — Sat, 20 Jan 2007 20:43:55 +0000

There is no way to restrict to a namespace. Namespaces are never units of protection. But if you’re using assemblies, you can use the ‘internal’ access modifier to restrict access to only within the assembly.

Is there a way of specifying which block or loop to break out of when working with nested loops?

admin — Sat, 20 Jan 2007 20:43:29 +0000

The easiest way is to use goto:

using System;
class BreakExample
{
public static void Main(String[] args) {
for(int i=0; i<3; i++)
{
Console.WriteLine(\”Pass {0}: \”, i);
for( int j=0 ; j<100 ; j++ )
{
if ( j == 10)
goto done;
Console.WriteLine(\”{0} \”, j);
}
Console.WriteLine(\”This will not print\”);
}
done:
Console.WriteLine(\”Loops complete.\”);
}
}

Is there a way to force garbage collection?

admin — Sat, 20 Jan 2007 20:43:00 +0000

Yes. Set all references to null and then call System.GC.Collect(). If you need to have some objects destructed, and System.GC.Collect() doesn’t seem to be doing it for you, you can force finalizers to be run by setting all the references to the object to null and then calling System.GC.RunFinalizers().

Is there an equivalent of exit() for quitting a C# .NET application?

admin — Sat, 20 Jan 2007 20:42:36 +0000

Yes, you can use System.Environment.Exit(int exitCode) to exit the application or Application.Exit() if it’s a Windows Forms app.

Is there any sample C# code for simple threading?

admin — Sat, 20 Jan 2007 20:41:40 +0000

Yes:

using System;
using System.Threading;
class ThreadTest
{
public void runme()
{
Console.WriteLine(\”Runme Called\”);
}
public static void Main(String[] args)
{
ThreadTest b = new ThreadTest();
Thread t = new Thread(new ThreadStart(b.runme));
t.Start();
}
}

Is there regular expression (regex) support available to C# developers?

admin — Sat, 20 Jan 2007 20:41:11 +0000

Yes. The .NET class libraries provide support for regular expressions. Look at the System.Text.RegularExpressions namespace.

My switch statement works differently than in C++! Why?

admin — Sat, 20 Jan 2007 20:40:45 +0000

C# does not support an explicit fall through for case blocks. The following code is not legal and will not compile in C#:

switch(x)
{
case 0: // do something
case 1: // do something as continuation of case 0
default: // do something in common with
//0, 1 and everything else
break;
}

To achieve the same effect in C#, the code must be modified as shown below (notice how the control flows are explicit):

class Test
{
public static void Main() {
int x = 3;
switch(x)
{
case 0: // do something
goto case 1;
case 1: // do something in common with 0
goto default;
default: // do something in common with 0, 1, and anything else
break;
}
}
}

What is the difference between a struct and a class in C#?

admin — Sat, 20 Jan 2007 20:40:16 +0000

From language spec: The list of similarities between classes and structs is as follows. Longstructs can implement interfaces and can have the same kinds of members as classes. Structs differ from classes in several important ways; however, structs are value types rather than reference types, and inheritance is not supported for structs. Struct values are stored on the stack or in-line. Careful programmers can sometimes enhance performance through judicious use of structs. For example, the use of a struct rather than a class for a Point can make a large difference in the number of memory allocations performed at runtime. The program below creates and initializes an array of 100 points. With Point implemented as a class, 101 separate objects are instantiated-one for the array and one each for the 100 elements.

What is the equivalent to regsvr32 and regsvr32 /u a file in .NET development?

admin — Sat, 20 Jan 2007 20:39:49 +0000

Try using RegAsm.exe. Search MSDN on Assembly Registration Tool.

What is the syntax for calling an overloaded constructor within a constructor (this() and constructorname() does not compile)?

admin — Sat, 20 Jan 2007 20:39:19 +0000

The syntax for calling another constructor is as follows: class B { B(int i) { } } class C : B { C() : base(5) // call base constructor B(5) { } C(int i) : this() // call C() { } public static void Main() {} }