Interview Questions Part 2 - Oracle , DotNet , SQL , UML , Javascript , AJAX
Question 1 :
What’s the Difference Between <%# i %> and <%= i %>?
Answer 1 :
We can use two constructs to access page-level variables in an ASP.NET web template:
data binding syntax
Data binding—the hierarchical mapping of control properties to data container values—is specified by the tags. Code located within a
code block is only executed when the DataBind method of its parent controlcontainer is invoked.
code rendering syntax
The code tags output content to the browser. This content could
be hard-coded, or it may contain page-level variables.
Question 2 :
Difference between Static and Instance Constructor ?
Answer 2 :
The static constructor executes at most once in a given application domain. The execution of a static constructor is triggered by the first of the following events to occur within an application domain:
• An instance of the class type is created.
• Any of the static members of the class type are referenced.
where as
Instance constructor can execute more than once.
Instance constructor executes when an instance of the class type is created.
Question 3 :
What is use of private constructor in C# ?
Answer 3 :
If a class contains only static members and isn’t intended to be instantiated, adding an empty private instance constructor will prevent instantiation.
Question 4 :
State whether the C# code : var z = null; is okay or not ?
Answer 4 :
Above code would give an error as null does not have
Question 5:
State whether below code would give compilation error or not ?
delegate string Delegate1(object o);
delegate object Delegate2(string s);
static string Dispaly(object o) {
return "Display";
}
static void Main(string[] args)
{
Delegate1 d1 = Display;
Delegate2 d2 = Display;
}
Answer 5:
It will give no compilation error .
Question 6 :
State whether below overload methods will give compilation erro or not ?Class Test
{
void SetX(ref int x)
{
x = 1;
}
void SetX(out int x)
{
X = 2;
}
}
Answer 6 :
Gives a compilation error.
SetX method cannot define overloaded methods that differ only on ref and out
Question 7 :
Whether b.x =1 statement in class A and class B is okay or not ?public class A
{
int x;
static void SetX(B b)
{
b.x = 1; }
}
public class B : A
{
static void SetX(B b)
{
b.x = 1;
}
}
Answer 7:
b.x = 1 in Class A is fine.
b.x = 1 in Class B gives compilation error
Help :
As x is private field in Class A hence accessible within Class A
As x is private field in Class A and hence not accessible in Class B
Question 8 :
Can namespace declaration have access modifiers ?
Answer 8 :
No . Namespace declaration cannot have access modifiers.
Help
Namespaces implicitly have public declared accessibility. No access modifiers and attributes are allowed on namespace declarations
Question 9 :
Is static void Main(int a) {...} a valid entry point for C# program ?
Answer 9:
No
Hint :
Entry point method is always named Main, and can have one of the following signatures:
static void Main() {...}
static void Main(string[] args) {...}
static int Main() {...}
static int Main(string[] args) {...}
The entry point may optionally have one formal parameter. The parameter may have any name, but the type of the parameter must be string[].
Question 10 :
How to create read only property in C# ?
Answer 10 :
A property that has only a get accessor is a read-only property .
Example :
public int Count {
get { return count; }
}
public int Capacity {
get {
return items.Length;
}
}
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