41⟩ How do I convert a string to an int in C#?
Here's an example: using System;
class StringToInt
{
public static void Main()
{
String s = "105";
int x = Convert.ToInt32(s);
Console.WriteLine(x);
}
}
C# (Sharp) Programming Language
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“Learn C# (Sharp) Programming Language by Interview Questions and Answers”
163 C# (Sharp) Programming Language Questions And Answers
42⟩ What is the .NET datatype that allows the retrieval of data by a unique key?
HashTable.
43⟩ How do you mark a method obsolete?
[Obsolete] public int Foo() {...}
or
[Obsolete("This is a message describing why this method is obsolete")] public int Foo() {...}
Note: The O in Obsolete is always capitalized.
44⟩ What is the difference between a Struct and a Class?
Structs are value-type variables and are thus saved on the stack, additional overhead but faster retrieval. Another difference is that structs cannot inherit.
45⟩ What does the keyword “virtual” declare for a method or property?
The method or property can be overridden.
46⟩ How is method overriding different from method overloading?
When overriding a method, you change the behavior of the method for the derived class. Overloading a method simply involves having another method with the same name within the class.
47⟩ What are the different ways a method can be overloaded?
Different parameter data types, different number of parameters, different order of parameters.
48⟩ How do you implement thread synchronization (Object.Wait, Notify,and CriticalSection) in C#?
You want the lock statement, which is the same as Monitor Enter/Exit:
lock(obj) { // code }
translates to
try {
CriticalSection.Enter(obj);
// code
}
finally
{
CriticalSection.Exit(obj);
}
49⟩ What is a multicast C# delegate?
A delegate that has multiple handlers assigned to it. Each assigned handler (method) is called.
50⟩ How do you generate documentation from the C# file commented properly with a command-line compiler?
Compile it with the /doc switch.
51⟩ What does assert() method 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.
52⟩ How do you debug an ASP.NET Web application?
Attach the aspnet_wp.exe process to the DbgClr debugger.
53⟩ What are three test cases you should go through in unit testing?
1. Positive test cases (correct data, correct output).
2. Negative test cases (broken or missing data, proper handling).
3. Exception test cases (exceptions are thrown and caught properly).
54⟩ Explain ACID rule of thumb for transactions in C#.
A transaction must be:
1. Atomic - it is one unit of work and does not dependent on previous and following transactions.
2. Consistent - data is either committed or roll back, no “in-between” case where something has been updated and something hasn’t.
3. Isolated - no transaction sees the intermediate results of the current transaction).
4. Durable - the values persist if the data had been committed even if the system crashes right after.
55⟩ What does the Initial Catalog parameter define in the connection string?
The database name to connect to.
56⟩ How is 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.
57⟩ What are the ways to deploy an assembly?
An MSI installer, a CAB archive, and XCOPY command.
58⟩ When should you call the garbage collector in .NET?
As a good rule, you should not call the garbage collector. However, you could call the garbage collector when you are done using a large object (or set of objects) to force the garbage collector to dispose of those very large objects from memory. However, this is usually not a good practice.
59⟩ How do you convert a value-type to a reference-type?
Use Boxing.
60⟩ How do you directly call a native function exported from a DLL?
Here’s a quick example of the DllImport attribute in action:
using System.Runtime.InteropServices;
class C
{
[DllImport("user32.dll")]
public static extern int MessageBoxA
(int h, string m, string c, int type);
public static int Main()
{
return MessageBoxA(0, "Hello World!", "Caption", 0);
}
}
This example shows the minimum requirements for declaring a C# method that is implemented in a native DLL. The method C.MessageBoxA() is declared with the static and external modifiers, and has the DllImport attribute, which tells the compiler that the implementation comes from the user32.dll, using the default name of MessageBoxA. For more information, look at the Platform Invoke tutorial in the documentation.
