21⟩ What namespaces are necessary to create a localized application?
System.Globalization, System.Resources.
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163 C# (Sharp) Programming Language Questions And Answers
22⟩ I was trying to use an out int parameter in one of my functions. How should I declare the variable that I am passing to it?
You should declare the variable as an int, but when you pass it in you must specify it as ‘out’, like the following: int i; foo(out i); where foo is declared as follows:
[return-type] foo(out int o) { }
23⟩ 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 is 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.
24⟩ What is the difference between // comments, /* */ comments and /// comments?
Single-line, multi-line and XML documentation comments.
25⟩ Explain the three services model (three-tier application). Presentation (UI), business (logic and underlying code) and data (from storage or other sources).
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).
26⟩ How do I port "synchronized" functions from Visual J++ to C#?
Original Visual J++ code: public synchronized void Run()
{
// function body
}
Ported C# code: class C
{
public void Run()
{
lock(this)
{
// function body
}
}
public static void Main() {}
}
27⟩ How does one compare strings in C#?
In the past, you had to call .ToString() on the strings when using the == or != operators to compare the strings’ values. That will still work, but the C# compiler now automatically compares the values instead of the references when the == or != operators are used on string types. If you actually do want to compare references, it can be done as follows: if ((object) str1 == (object) str2) { } Here’s an example showing how string compares work:
using System;
public class StringTest
{
public static void Main(string[] args)
{
Object nullObj = null; Object realObj = new StringTest();
int i = 10;
Console.WriteLine("Null Object is [" + nullObj + "] "
+ "Real Object is [" + realObj + "] "
+ "i is [" + i + "] ");
// Show string equality operators
string str1 = "foo";
string str2 = "bar";
string str3 = "bar";
Console.WriteLine("{0} == {1} ? {2}", str1, str2, str1 == str2 );
Console.WriteLine("{0} == {1} ? {2}", str2, str3, str2 == str3 );
}
}
Output:
Null Object is []
Real Object is [StringTest]
i is [10]
foo == bar ? False
bar == bar ? True
28⟩ Does C# support #define for defining global constants?
No. If you want to get something that works like the following C code:
#define A 1
use the following C# code: class MyConstants
{
public const int A = 1;
}
Then you use MyConstants.A where you would otherwise use the A macro.
Using MyConstants.A has the same generated code as using the literal 1.
29⟩ Does C# support parameterized properties?
No. C# does, however, support the concept of an indexer from language spec. An indexer is a member that enables an object to be indexed in the same way as an array. Whereas properties enable field-like access, indexers enable array-like access. As an example, consider the Stack class presented earlier. The designer of this class may want to expose array-like access so that it is possible to inspect or alter the items on the stack without performing unnecessary Push and Pop operations. That is, Stack is implemented as a linked list, but it also provides the convenience of array access.
Indexer declarations are similar to property declarations, with the main differences being that indexers are nameless (the name used in the declaration is this, since this is being indexed) and that indexers include indexing parameters. The indexing parameters are provided between square brackets.
30⟩ Does C# support C type macros?
No. C# does not have macros. Keep in mind that what some of the predefined C macros (for example, __LINE__ and __FILE__) give you can also be found in .NET classes like System.Diagnostics (for example, StackTrace and StackFrame), but they'll only work on debug builds.
31⟩ Can you declare the override method static while the original method is non-static?
No, you cannot, the signature of the virtual method must remain the same, only the keyword virtual is changed to keyword override
32⟩ Does C# support multiple inheritance?
No, use interfaces instead.
33⟩ 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,
34⟩ What is the data provider name to connect to Access database?
Microsoft.Access.
35⟩ What is the wildcard character in SQL?
Let us 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%.
36⟩ What does the This window show in the debugger?
It points to the object that is pointed to by this reference. Object’s instance data is shown.
37⟩ What is an interface class in C#?
It is an abstract class with public abstract methods all of which must be implemented in the inherited classes.
38⟩ What is a multicast delegate in C#?
It is a delegate that points to and eventually fires off several methods.
39⟩ How do I get deterministic finalization in C#?
In a garbage collected environment, it's impossible to get true determinism. However, a design pattern that we recommend is implementing IDisposable on any class that contains a critical resource. Whenever this class is consumed, it may be placed in a using statement, as shown in the following example:
using(FileStream myFile = File.Open(@"c:temptest.txt",
FileMode.Open))
{
int fileOffset = 0;
while(fileOffset < myFile.Length)
{
Console.Write((char)myFile.ReadByte());
fileOffset++;
}
}
When myFile leaves the lexical scope of
the using, its dispose method will be called.
40⟩ Why do I get an error (CS1006) when trying to declare a method without specifying a return type?
If you leave off the return type on a method declaration, the compiler thinks you are trying to declare a constructor. So if you are trying to declare a method that returns nothing, use void. The following is an example: // This results in a CS1006 error public static staticMethod (mainStatic obj) // This will work as wanted public static void staticMethod (mainStatic obj)
