C# Interview Questions and Answers (958) - Page 4

NOTE: This is objective type question, Please click question title for correct answer.

NOTE: This is objective type question, Please click question title for correct answer.

NOTE: This is objective type question, Please click question title for correct answer.

String is an object (Reference Type).

Attributes are a mechanism for adding metadata, such as compiler instructions and other data about your data, methods, and classes, to the program itself. Attributes are inserted into the metadata and are visible through ILDasm and other metadata-reading tools. Attributes can be used to identify or use the data at runtime execution using .NET Reflection.

Data Reader is connected, read only forward only record set.
Dataset is in memory database that can store multiple tables, relations and constraints; moreover dataset is disconnected and is not aware of the data source.

Building a shared assembly does involve working with cryptographic keys. Only the public key is strictly needed when the assembly is being built. Compilers targeting the .NET Framework provide command line options (or use custom attributes) for supplying the public key when building the assembly. It is common to keep a copy of a common public key in a source database and point build scripts to this key. Before the assembly is shipped, the assembly must be fully signed with the corresponding private key. This is done using an SDK tool called SN.exe (Strong Name).
Strong name signing does not involve certificates like Authenticode does. There are no third party organizations involved, no fees to pay, and no certificate chains. In addition, the overhead for verifying a strong name is much less than it is for Authenticode. However, strong names do not make any statements about trusting a particular publisher. Strong names allow you to ensure that the contents of a given assembly haven't been tampered with, and that the assembly loaded on your behalf at run time comes from the same publisher as the one you developed against. But it makes no statement about whether you can trust the identity of that publisher.

An application domain (often AppDomain) is a virtual process that serves to isolate an application. All objects created within the same application scope (in other words, anywhere along the sequence of object activations beginning with the application entry point) are created within the same application domain. Multiple application domains can exist in a single operating system process, making them a lightweight means of application isolation.

An OS process provides isolation by having a distinct memory address space. While this is effective, it is also expensive, and does not scale to the numbers required for large web servers. The Common Language Runtime, on the other hand, enforces application isolation by managing the memory use of code running within the application domain. This ensures that it does not access memory outside the boundaries of the domain. It is important to note that only type-safe code can be managed in this way (the runtime cannot guarantee isolation when unsafe code is loaded in an application domain).

Garbage collection is a mechanism that allows the computer to detect when an object can no longer be accessed. It then automatically releases the memory used by that object (as well as calling a clean-up routine, called a "finalizer," which is written by the user). Some garbage collectors, like the one used by .NET, compact memory and therefore decrease your program's working set.

NOTE: This is objective type question, Please click question title for correct answer.

A top level class is a class that is not a nested class.

See what is nested class http://www.dotnetfunda.com/interview/exam281-what-is-nested-class.aspx

A Nested classes are classes within classes.

OR

A nested class is any class whose declaration occurs within the body of another class or interface.

For more details see http://www.codeproject.com/KB/cs/nested_csclasses.aspx

Partial class is a new functionality added in since .NET Framework 2.0 version. It allows to split us to split the definition of once class, struct, interface into multiple source files. Each source file contains a section of definition, and all parts are combined when the application is compiled.

For more detail see http://msdn.microsoft.com/en-us/library/wa80x488(VS.80).aspx

Extension method is a new feature in C# 3.0.

Extension methods allow existing classes to be extended without relying on inheritance or having to change the class's source code. This means that if you want to add some methods into the existing String class you can do it quite easily.

Here's a couple of rules to consider when deciding on whether or not to use extension methods:

* Extension methods cannot be used to override existing methods
* An extension method with the same name and signature as an instance method will not be called
* The concept of extension methods cannot be applied to fields, properties or events
* Use extension methods sparingly....overuse can be a bad thing!

For more details, see http://weblogs.asp.net/dwahlin/archive/2008/01/25/c-3-0-features-extension-methods.aspx

NOTE: This is objective type question, Please click question title for correct answer.

NOTE: This is objective type question, Please click question title for correct answer.

NOTE: This is objective type question, Please click question title for correct answer.

If no class is inhertited, by default a class inherit System.Object.

NOTE: This is objective type question, Please click question title for correct answer.

This is the new feature in C# 3.0. This enable us to declare a variable whose type is implicitly inferred from the expression used to initialize the variable.

eg.

var age = 10;

Because the initialization value (10) of the variable age is integer type of age will be treated as integer type of variable. There are few limitation of the var type of variables.

They are:

#. They can't be initialized as null.
#. They need to be declared and initialized in the same statement.
#. They can't be used as a member of the class.