C Sharp Interview Questions & Answers part 3


Q: – Explain how to configure Trace switches in the application’s .config file ?

switches are configured using the .config file

<add name="MyTraceSwitch" value="1" />
<add name="TraceSwitch2" value="1" />
both are on.

Q: – Explain how exceptions are handled by the common language runtime in .NET ?

The CLR uses a technique generally referred to as a two-pass exception review process. What this means is that the CLR will process an exception in two passes. In the first pass, the CLR will determine if there is a handler for the exception. This is done by reviewing the entries in the SEH table; specifically it looks at the Try Offset and Try Length flags to see if the exception occurred within a guarded block, and if so, whether the Flags entry dictates that a handler exists for this type of occurrence. Let's assume that the CLR did find a handler during the first pass. At that point the CLR begins a second pass of the SEH table during which it will work through the execution phase of the exception management process. So we can divide the two passes into a discovery pass, in which we determine whether there is a handler in this method context to handle the exception; and an execution pass, in which we actually execute the handler and any special rules.

When code throws an exception, the CLR looks up the call stack looking for a catch filter to handle the exception. When it finds the relevant catch block, before executing the code, it will execute all code in all finally blocks – starting from the try block that threw the exception and stopping with the catch filter that matches the exception. when the CLR encounters an exception for a method it will use the descriptors in the SEH table to determine how to handle the exception, which code block is affected, and what handler should be invoked.

Q: – Describe the different types of user-authored controls in NET ?

User authored controls are which not part of the .net framework library. It includes both custom controls and user controls.

  1. Custom Controls: They look similar to ASP.NET controls. They can be created in one of the 3 ways:-

    • Deriving a custom control from existing custom control.
    • Making a composite custom control by combining 2 or more existing controls
    • By creating a new control from scratch by deriving the control from its base class.
  2. User Controls: enables a part of ASP.NET page to be reused. The reusable part is in form of a control with the extension .ascx. They look like to be a group of ASP.NET controls which can be used over and over again.

Q: – Explain with code sample how to create a custom control ?

Steps to create a custom control:

  1. Create a new project.
  2. Add a custom control to the project.
  3. Change the name of the class you need to inherit the control from the base class. E.g. inherit the class from System.Windows.Forms.Button if the control s to be inherited from a button class.
  4. Implement the control with custom properties and featured needed by the control.
  5. Override the OnPaint method if the control’s appearance needs to be changed.
  6. Save the build the control
  7. Reference you control into another or the same project and use the control.

Submitted By:-Goyal Ankur            Email-ID: – goyal.ankur30@yahoo.in