C# Interview Questions, Part 2
21. What’s 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.
22. How can you overload a method? Different parameter data types, different number of parameters, different order of parameters.
23. If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor to an arbitrary base constructor? 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.
24. What’s 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.
25. What’s the advantage of using System.Text.StringBuilder over System.String? StringBuilder is more efficient in the cases, where a lot of manipulation is done to the text. Strings are immutable, so each time it’s being operated on, a new instance is created.
26. Can you store multiple data types in System.Array? No.
27. What’s the difference between the System.Array.CopyTo() and System.Array.Clone()? The first one performs a deep copy of the array, the second one is shallow.
28. How can you sort the elements of the array in descending order? By calling Sort() and then Reverse() methods.
29. What’s the .NET datatype that allows the retrieval of data by a unique key? HashTable.
30. What’s class SortedList underneath? A sorted HashTable.
31. Will finally block get executed if the exception had not occurred? Yes.
32. What’s the C# equivalent of C++ catch (…), which was a catch-all statement for any possible exception? A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}.
33. Can multiple catch blocks be executed? No, once the proper catch code fires off, the control is transferred to the finally block (if there are any), and then whatever follows the finally block.
34. Why is it a bad idea to throw your own exceptions? Well, if at that point you know that an error has occurred, then why not write the proper code to handle that error instead of passing a new Exception object to the catch block? Throwing your own exceptions signifies some design flaws in the project.
35. What’s a delegate? A delegate object encapsulates a reference to a method. In C++ they were referred to as function pointers.
36. What’s a multicast delegate? It’s a delegate that points to and eventually fires off several methods.
37. How’s the DLL Hell problem solved in .NET? Assembly versioning allows the application to specify not only the library it needs to run (which was available under Win32), but also the version of the assembly.
38. What are the ways to deploy an assembly? An MSI installer, a CAB archive, and XCOPY command.
39. What’s a satellite assembly? When you write a multilingual or multi-cultural application in .NET, and want to distribute the core application separately from the localized modules, the localized assemblies that modify the core application are called satellite assemblies.
40. What namespaces are necessary to create a localized application? System.Globalization, System.Resources.
C# interview questions and answers
1. What’s the advantage of using System.Text.StringBuilder over System.String?
StringBuilder is more efficient in cases where a large amount of manipulation is done in the text. Strings are immutable, so it is increasingly being operated, a new instance is created.
2. Can you store multiple data types in System.Array?
No.
3. What’s the difference between the System.Array.CopyTo() and System.Array.Clone()?
The first three performs a deep copy of the array, the second three is shallow.
4. How can you sort the elements of the array in descending order?
By calling Sort() and then Reverse() methods.
5. What’s the C# equivalent of C++ catch (…), which was a catch-all statement for any possible exception?
A catch block that catches the exception of type Process.Exception. You can also omit the parameter information type in this case and write catch {}.
6. Why is it a bad idea to throw your own exceptions?
Well, if that point is known that an error has occurred, why not write the code of law to resolve this error, instead of passing a new Exception object to the catch block? Start your own exclusions means that some design flaws in the project.
7. What’s a delegate?
A delegate object encapsulates a reference to a system. In C++ they were referred to as function pointers.
8. How’s the DLL Hell problem solved in .NET?
Assembly versions allows the application to specify not only the library it needs to function (which was available under Win32), but also the version of the Assembly.
9. What are the ways to deploy an assembly?
An MSI installer, a CAB archive, and XCOPY command.
10. What’s a satellite assembly?
When writing a multilingual application in multi-cultural. NET, and need to deliver the core application separately from the localized modules, the localized assemblies that change the core application are called satellite assemblies.
11. What’s the difference between // comments, /* */ comments and /// comments?
Single-line, multi-line and XML documentation comments.
12. How do you generate documentation from the C# file commented properly with a command-line compiler?
Compile it with a /doc switch.
13. What’s the difference between <c> and <code> XML documentation tag?
Single line code example and multiple-line code example.
C# Interview Questions & Answers :
1. Does C# support multiple-inheritance?
No.
2. Who is a protected class-level variable available to?
It is available to any sub-class (a class inheriting this class).
3. Are private class-level variables inherited?
Yes, but they are not accessible. Although they are not visible or accessible via the class interface, they are inherited.
4. Describe the accessibility modifier “protected internal”.
It is available to classes that are within the same assembly and derived from the specified base class.
5. What’s the top .NET class that everything is derived from?
System.Object.
6. What does the term immutable mean?
The data value may not be changed. Note: The variable value may be changed, but the original immutable data value was discarded and a new data value was created in memory.
7. What’s the difference between System.String and System.Text.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.
8. What’s the advantage of using System.Text.StringBuilder over System.String?
StringBuilder is more efficient in cases where there is a large amount of string manipulation. Strings are immutable, so each time a string is changed, a new instance in memory is created.
9. Can you store multiple data types in System.Array?
No.
10. What’s the difference between the System.Array.CopyTo() and System.Array.Clone() ?
The Clone() method returns a new array (a shallow copy) object containing all the elements in the original array. The CopyTo() method copies the elements into another existing array. Both perform a shallow copy. A shallow copy means the contents (each array element) contains references to the same object as the elements in the original array. A deep copy (which neither of these methods performs) would create a new instance of each element's object, resulting in a different, yet identacle object.
C# Interview Questions and Answers
1) The C# keyword ?int? maps to which .NET type?
-
System.Int16
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System.Int32
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System.Int64
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System.Int128
2) Which of these string definitions will prevent escaping on backslashes in C#?
-
string s = #?n Test string?;
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string s = ??n Test string?;
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string s = @?n Test string?;
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string s = ?n Test string?;
3) Which of these statements correctly declares a two-dimensional array in C#?
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int[,] myArray;
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int[][] myArray;
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int[2] myArray;
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System.Array[2] myArray;
4) If a method is marked as protected internal who can access it?
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Classes that are both in the same assembly and derived from the declaring class.
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Only methods that are in the same class as the method in question.
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Internal methods can be only be called using reflection.
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Classes within the same assembly, and classes derived from the declaring class.
5) What is boxing?
a) Encapsulating an object in a value type.
b) Encapsulating a copy of an object in a value type.
c) Encapsulating a value type in an object.
d) Encapsulating a copy of a value type in an object.
6) What compiler switch creates an xml file from the xml comments in the files in an assembly?
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/text
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/doc
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/xml
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/help
7) What is a satellite Assembly?
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A peripheral assembly designed to monitor permissions requests from an application.
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Any DLL file used by an EXE file.
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An assembly containing localized resources for another assembly.
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An assembly designed to alter the appearance or ?skin? of an application.
What is a delegate?
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A strongly typed function pointer.
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A light weight thread or process that can call a single method.
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A reference to an object in a different process.
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An inter-process message channel.
9) How does assembly versioning in .NET prevent DLL Hell?
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The runtime checks to see that only one version of an assembly is on the machine at any one time.
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.NET allows assemblies to specify the name AND the version of any assemblies they need to run.
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The compiler offers compile time checking for backward compatibility.
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It doesn?t.
10) Which ?Gang of Four? design pattern is shown below?
public class A {
private A instance;
private A() {
}
public
static A Instance {get
{
if ( A == null )
A = new A();
return instance;
}
}
}
-
Factory
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Abstract Factory
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Singleton
-
Builder
40 C# interview questions and answers
- What’s the difference between the Debug class and Trace class? Documentation looks the same. Use Debug class for debug builds, use Trace class for both debug and release builds.
- Why are there five tracing levels in System.Diagnostics.TraceSwitcher? The tracing dumps can be quite verbose and for some applications that are constantly running you run the risk of overloading the machine and the hard drive there. Five levels range from None to Verbose, allowing to fine-tune the tracing activities.
- Where is the output of TextWriterTraceListener redirected? To the Console or a text file depending on the parameter passed to the constructor.
- How do you debug an ASP.NET Web application? Attach the aspnet_wp.exe process to the DbgClr debugger.
- What’s class SortedList underneath? A sorted HashTable.
- Will finally block get executed if the exception had not occurred? Yes.
- What’s the C# equivalent of C++ catch (…), which was a catch-all statement for any possible exception? A catch block that catches the exception of type System.Exception. You can also omit the parameter data type in this case and just write catch {}.
- Can multiple catch blocks be executed? No, once the proper catch code fires off, the control is transferred to the finally block (if there are any), and then whatever follows the finally block.
- What’s the advantage of using System.Text.StringBuilder over System.String? StringBuilder is more efficient in the cases, where a lot of manipulation is done to the text. Strings are immutable, so each time it’s being operated on, a new instance is created.
- Can you store multiple data types in System.Array? No.
- What’s the difference between the System.Array.CopyTo() and System.Array.Clone()? The first one performs a deep copy of the array, the second one is shallow.
- How can you sort the elements of the array in descending order? By calling Sort() and then Reverse() methods.
- What’s the .NET datatype that allows the retrieval of data by a unique key? HashTable.
- What’s a satellite assembly? When you write a multilingual or multi-cultural application in .NET, and want to distribute the core application separately from the localized modules, the localized assemblies that modify the core application are called satellite assemblies.
- What namespaces are necessary to create a localized application? System.Globalization, System.Resources.
- What’s the difference between // comments, /* */ comments and /// comments? Single-line, multi-line and XML documentation comments.
- How do you generate documentation from the C# file commented properly with a command-line compiler? Compile it with a /doc switch.
- What’s the difference between <c> and <code> XML documentation tag? Single line code example and multiple-line code example.
- Why is it a bad idea to throw your own exceptions? Well, if at that point you know that an error has occurred, then why not write the proper code to handle that error instead of passing a new Exception object to the catch block? Throwing your own exceptions signifies some design flaws in the project.
- What is the wildcard character in SQL? Let’s say you want to query database with LIKE for all employees whose name starts with La. The wildcard character is %, the proper query with LIKE would involve ‘La%’.
- Explain ACID rule of thumb for transactions. Transaction must be Atomic (it is one unit of work and does not dependent on previous and following transactions), Consistent (data is either committed or roll back, no “in-between” case where something has been updated and something hasn’t), Isolated (no transaction sees the intermediate results of the current transaction), Durable (the values persist if the data had been committed even if the system crashes right after).
- What connections does Microsoft SQL Server support? Windows Authentication (via Active Directory) and SQL Server authentication (via Microsoft SQL Server username and passwords).
- What is a pre-requisite for connection pooling? Multiple processes must agree that they will share the same connection, where every parameter is the same, including the security settings.
- What’s a delegate? A delegate object encapsulates a reference to a method. In C++ they were referred to as function pointers.
- What’s a multicast delegate? It’s a delegate that points to and eventually fires off several methods.
- How’s the DLL Hell problem solved in .NET? Assembly versioning allows the application to specify not only the library it needs to run (which was available under Win32), but also the version of the assembly.
- What are the ways to deploy an assembly? An MSI installer, a CAB archive, and XCOPY command.
- Is XML case-sensitive? Yes, so <Student> and <student> are different elements.
- What debugging tools come with the .NET SDK? CorDBG – command-line debugger, and DbgCLR – graphic debugger. Visual Studio .NET uses the DbgCLR. To use CorDbg, you must compile the original C# file using the /debug switch.
- What does the This window show in the debugger? It points to the object that’s pointed to by this reference. Object’s instance data is shown.
- What does assert() do? In debug compilation, assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition is true.
- What are three test cases you should go through in unit testing? Positive test cases (correct data, correct output), negative test cases (broken or missing data, proper handling), exception test cases (exceptions are thrown and caught properly).
- Why would you use untrusted verificaion? Web Services might use it, as well as non-Windows applications.
- What does the parameter Initial Catalog define inside Connection String? The database name to connect to.
- What’s the data provider name to connect to Access database? Microsoft.Access.
- What does Dispose method do with the connection object? Deletes it from the memory.
- Can you change the value of a variable while debugging a C# application? Yes, if you are debugging via Visual Studio.NET, just go to Immediate window.
- Explain the three services model (three-tier application). Presentation (UI), business (logic and underlying code) and data (from storage or other sources).
- What are advantages and disadvantages of Microsoft-provided data provider classes in ADO.NET? SQLServer.NET data provider is high-speed and robust, but requires SQL Server license purchased from Microsoft. OLE-DB.NET is universal for accessing other sources, like Oracle, DB2, Microsoft Access and Informix, but it’s a .NET layer on top of OLE layer, so not the fastest thing in the world. ODBC.NET is a deprecated layer provided for backward compatibility to ODBC engines.
- What’s the role of the DataReader class in ADO.NET connections? It returns a read-only dataset from the data source when the command is executed.
C# interview questions
- What’s the advantage of using System.Text.StringBuilder over System.String? StringBuilder is more efficient in the cases, where a lot of manipulation is done to the text. Strings are immutable, so each time it’s being operated on, a new instance is created.
- Can you store multiple data types in System.Array? No.
- What’s the difference between the System.Array.CopyTo() and System.Array.Clone()? The first one performs a deep copy of the array, the second one is shallow.
- How can you overload a method? Different parameter data types, different number of parameters, different order of parameters.
- If a base class has a bunch of overloaded constructors, and an inherited class has another bunch of overloaded constructors, can you enforce a call from an inherited constructor to an arbitrary base constructor? 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.
- What’s 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.
- What’s a delegate? A delegate object encapsulates a reference to a method. In C++ they were referred to as function pointers.
- What’s a multicast delegate? It’s a delegate that points to and eventually fires off several methods.
More: http://tipsinterview.com/doc/Csharp_Interview_Questions.doc
General IT Interview Tips
Getting job in technical industry dealing with information technology is a lucrative career option for many people around the world. In today’s world, it is indeed a high demand job for a huge bunch of individuals. However, it is not so easy to crack like many other tech interviews. It needs dedication, hard work and thorough preparation along with talent and knowledge.
If you are aspiring IT applicants, you may consult different online and offline guides in order to find out potential interview questions that focus on the crucial segments of an IT interview process. Typically, IT interview questions aim at assessing knowledge, skills, and abilities that are relevant to the performance of job. So while facing an interview, the primary step of an applicant should be to review the sample interview questions thoroughly and to concentrate on the answer tips which are provided in most of the standard guide books. In fact, Internet offers abundant information on this aspect.
IT itself is a vast area of study. In fact, there is a great variety of IT interview questions depending on the specification. It can include questions on programming, system analysis, microcomputer information projects, system design, system testing, system installing, documenting, maintaining and managing computer application program, knowledge regarding computer language, report generations, application generations, designing of high level of interpreters, preparing system specifications, technical documentation for applications, database management, operational support, interfacing between technical and non-technical personnel, etc.
While taking your preparation, you must focus on some key aspects. For example, if you are consulting an interview guide book, you try to explore tough questions including follow-up questions. You try to provide natural and prompt answer. Be analytical while you find the answer which you think little complicated. Try to break down the answers into small segments. While searching for jobs in IT sector, you must be sure of enhancing your analytical strength. Put enough time to rehearse and improve your problem solving ability. You may even have to face questions directly on your analytical abilities, such as how you would like to rate your analytical skill and why.
