1. how do you box a primitive data type variable?
To pass it by reference.
2. How do you convert a string into an integer in .NET?
Int32.Parse( string)
The value-type variables are not garbage-collected, they just fall off the stack when they fall out of scope, the reference-type objects are picked up by GC when their references go null.
4. Where do the reference-type variables go in the RAM?
The references go on the stack, while the objects themselves go on the heap.
6. Speaking of Boolean data types, Whats different between C# and /C++?
There's no conversion between 0 and false, as well as any other number and true, like in C/C++.
8. Whats the difference between Struct and class in C#?
Structs cannot be inherited.
Structs are passed by value, not by reference.
Struct is stored on the stack, not the heap.
Explain encapsulation.
The implementation is hidden, the interface is exposed.
9. Whats the access level of the visibility type internal?
Current application.
10. How do you initialize a two-dimensional array that you don't know the dimensions of?
int [ , ] myArray; //declaration
myArray = new int [5, 8]; //actual initialization
11. What are valid signatures for the Main function?
public static void Main ()
public static int Main ()
public static void Main ( string[] args )
public static int Main (string[] args )
12. How do you initiate a string without escaping each backslash?
Put an @ sign in front of the double-quoted string.
16 bits (Unicode).
15. Whats the difference between System. String and System.StringBuilder classes?
System. String is immutable; System.StringBuilder was designed with the purpose of having a mutable string where a variety of operations can be performed
Yes, just place a colon, and then keyword base (parameter list to invoke the appropriate constructor) in the overloaded constructor definition inside the inherited class.
17. How can you overload a method?
Different parameter data types, different number of parameters, different order of parameters.
18. Whats the difference between an interface and abstract class?
In the interface all methods must be abstract, in the abstract class some methods can be concrete. In the interface no accessibility modifiers are allowed, which is ok in abstract classes.
19. And if they have conflicting method names?
It's up to you to implement the method inside your own class, so implementation is left entirely up to you. This might cause a problem on a higher-level scale if similarly named methods from different interfaces expect different data, but as far as compiler cares you're okay.
20. Why cant you specify the accessibility modifier for methods inside the interface?
They all must be public. Therefore, to prevent you from getting the false impression that you have any freedom of choice, you are not allowed to specify any accessibility, it's public by default.
It's an abstract class with public abstract methods all of which must be implemented in the inherited classes.
When at least one of the methods in the class is abstract. When the class itself is inherited from an abstract class, but not all base abstract methods have been over-ridden.
A class that cannot be instantiated. A concept in C++ known as pure virtual method. A class that must be inherited and have the methods over-ridden. Essentially, it's a#4767d0print for a class without any implementation.
24. Hows method overriding different from overloading?
When overriding, you change the method behavior for a derived class. Overloading simply involves having a method with the same name within the class.
26. When you inherit a protected class-level variable, who is it available to?
Classes in the same namespace.
27. Whats the implicit name and type of the parameter that gets passed into the class set method?
Value, and it's data type depends on Whatever variable we're changing.
How do you inherit from a class in C#?
Place a colon and then the name of the base class. Notice that it's double colon in C++.
28. How do I administer security for my machine? For an enterprise?
The .NET Framework includes the .NET Framework Configuration tool, an MMC snap-in (mscorcfg.msc), to configure several aspects of the CLR including security policy. The snap-in not only supports administering security policy on the local machine, but also creates enterprise policy deployment packages compatible with System Management Server and Group Policy. A command line utility, CASPol.exe, can also be used to script policy changes on the computer. In order to run either tool, in a command prompt, change the current directory to the installation directory of the .NET Framework (located in %windir%Microsoft.NetFrameworkv1.0.2914.16) and type mscorcfg.msc or caspol.exe.
29. How do I make it so that code runs when the security system is stopping it?
Security exceptions occur when code attempts to perform actions for which it has not been granted permission. Permissions are granted based on What is known about code; especially its location. For example, code run from the Internet is given fewer permissions than that run from the local machine because experience has proven that it is generally less reliable. So, to allow code to run that is failing due to security exceptions, you must increase the permissions granted to it. One simple way to do so is to move the code to a more trusted location (such as the local file system). But this won't work in all cases (web applications are a good example, and intranet applications on a corporate network are another). So, instead of changing the code's location, you can also change security policy to grant more permissions to that location. This is done using either the .NET Framework Configuration tool or the code access security policy utility (caspol.exe). If you are the code's developer or publisher, you may also digitally sign it and then modify security policy to grant more permissions to code bearing that signature. When taking any of these actions, however, remember that code is given fewer permissions because it is not from an identifiably trustworthy source-before you move code to your local machine or change security policy, you should be sure that you trust the code to not perform malicious or damaging actions.
30. Why does my code get a security exception when I run it from a network shared drive?
Default security policy gives only a restricted set of permissions to code that comes from the local intranet zone. This zone is defined by the Internet Explorer security settings, and should be configured to match the local network within an enterprise. Since files named by UNC or by a mapped drive (such as with the NET USE command) are being sent over this local network, they too are in the local intranet zone.
The default is set for the worst case of an unsecured intranet. If your intranet is more secure you can modify security policy (with the .NET Framework Configuration tool or the CASPol tool) to grant more permissions to the local intranet, or to portions of it (such as specific machine share names).
31. What do I have to do to make my code work with the security system?
Usually, not a thing-most applications will run safely and will not be exploitable by malicious attacks. By simply using the standard class libraries to access resources (like files) or perform protected operations (such as a reflection on private members of a type), security will be enforced by these libraries. The one simple thing application developers may want to do is include a permission request (a form of declarative security) to limit the permissions their code may receive (to only those it requires). This also ensures that if the code is allowed to run, it will do so with all the permissions it needs.
Only developers writing new base class libraries that expose new kinds of resources need to work directly with the security system. Instead of all code being a potential security risk, code access security constrains this to a very small bit of code that explicitly overrides the security system.
32. Can I use the Win32 API from a .NET Framework program?
Yes. Using platform invoke, .NET Framework programs can access native code libraries by means of static DLL entry points.
Here is an example of C# calling the Win32 Message Box function:
using System;
using System.Runtime.InteropServices;
class MainApp
{
[DllImport("user32.dll", EntryPoint="MessageBox")]
public static extern int MessageBox(int hWnd, String strMessage, String strCaption, uint uiType);
public static void Main()
{
MessageBox( 0, "Hello, this is PInvoke in operation!", ".NET", 0 );
}
}
33. Can .NET Framework components be used from a COM program?
Yes. Managed types you build today can be made accessible from COM, and in the common case the configuration is totally automatic. There are certain new features of the managed development environment that are not accessible from COM. For example, static methods and parameterized constructors cannot be used from COM. In general, it is a good idea to decide in advance who the intended user of a given type will be. If the type is to be used from COM, you may be restricted to using those features that are COM accessible.
Depending on the language used to write the managed type, it may or may not be visible by default.
Specifically, .NET Framework components are accessed from COM by using a COM callable wrapper (CCW). This is similar to an RCW (see previous question), but works in the opposite direction. Again, if the .NET Framework development tools cannot automatically generate the wrapper, or if the automatic behavior is not What you want, a custom CCW can be developed.
34. Can I use COM objects from a .NET Framework program?
Yes. Any COM component you have deployed today can be used from managed code, and in common cases the adaptation is totally automatic.
Specifically, COM components are accessed from the .NET Framework by use of a runtime callable wrapper (RCW). This wrapper turns the COM interfaces exposed by the COM component into .NET Framework-compatible interfaces. For OLE automation interfaces, the RCW can be generated automatically from a type library. For non-OLE automation interfaces, a developer may write a custom RCW and manually map the types exposed by the COM interface to .NET Framework-compatible types.
35. How do in-process and cross-process communication work in the Common Language Runtime?
There are two aspects to in-process communication: between contexts within a single application domain, or across application domains. Between contexts in the same application domain, proxies are used as an interception mechanism. No marshaling/serialization is involved. When crossing application domains, we do marshaling/serialization using the runtime binary protocol.
Cross-process communication uses a pluggable channel and formatter protocol, each suited to a specific purpose.
If the developer specifies an endpoint using the tool soapsuds.exe to generate a metadata proxy, HTTP channel with SOAP formatter is the default.
If a developer is doing explicit remoting in the managed world, it is necessary to be explicit about What channel and formatter to use. This may be expressed administratively, through configuration files, or with API calls to load specific channels. Options are:
HTTP channel w/ SOAP formatter (HTTP works well on the Internet, or anytime traffic must travel through firewalls)
TCP channel w/ binary formatter (TCP is a higher performance option for local-area networks (LANs))
When making transitions between managed and unmanaged code, the COM infrastructure (specifically, DCOM) is used for remoting. In interim releases of the CLR, this applies also to serviced components (components that use COM+ services). Upon final release, it should be possible to configure any removable component.
Distributed garbage collection of objects is managed by a system called "le
