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Delphi Technical Latest Sample Placement Paper1. How are the wait/signal operations for monitor different from those
for semaphores?
ANS: If a process in a monitor signal and no task is waiting on the
condition variable, the signal is lost. So this allows easier program
design. Whereas in semaphores, every operation affects the value of
the semaphore, so the wait and signal operations should be perfectly
balanced in the program.
2. How do I create a subscript operator for a Matrix class?
ANS: Use operator () rather than operator [].When you have multiple subscripts, the cleanest way to do it is with
operator () rather than with operator []. The reason is that operator []
always takes exactly one parameter, but operator () can take any
number of parameters (in the case of a rectangular matrix, two
parameters are needed).
For example:
class Matrix {
public:
Matrix(unsigned rows, unsigned cols);
double& operator() (unsigned row, unsigned col); subscript operators
often come in pairs double operator() (unsigned row, unsigned col)
const; subscript operators often come in pairs
...
~Matrix(); // Destructor
Matrix(const Matrix& m); // Copy constructor
Matrix& operator= (const Matrix& m); // Assignment operator
... private:
unsigned rows_, cols_;
double* data_;
};
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inline
Matrix::Matrix(unsigned rows, unsigned cols)
: rows_ (rows)
, cols_ (cols)
//data_ = rows_ || col >= cols_)throw BadIndex("Matrix subscript out of bounds");
return data_[cols_*row + col];
}
inline
double Matrix::operator() (unsigned row, unsigned col) const
{
if (row >= rows_ || col >= cols_)
throw BadIndex("const Matrix subscript out of bounds");return data_[cols_*row + col];
}
Then you can access an element of Matrix m using m(i,j) rather than
m[i][j]:
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int main()
{
Matrix m(10,10); m(5,8) = 106.15; std::cout
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10.What is Zorder Method?
ANS: Object.Zorder = 1 or 0 Place a Specified mdiform form or control
at the front or back of the z-order with n its Graphical Level.11.How can I customize the serialization process?
I.e. how can one have a control over the serialization process?
ANS: Yes it is possible to have control over serialization process. The
class should implement Externalizable interface. This interface contains
two methods namely readExternal and writeExternal. You should
implement these methods and write the logic for customizing the
serialization process.
12.What is the different between Microsoft ODBC Driver and OracleOBDC Driver?
ANS: Microsoft ODBC driver will support all the methods and properties
of Visual Basic. Whereas the Oracle not.
13.What is the common usage of serialization?
ANS: Whenever an object is to be sent over the network, objects need
to be serialized. Moreover if the state of an object is to be saved,
objects need to be serialized.14.How do I serialize an object to a file?
ANS: The class whose instances are to be serialized should implement
an interface Serializable. Then you pass the instance to the
ObjectOutputStream which is connected to a fileoutputstream. This will
save the object to a file.
15.What one should take care of while serializing the object?
ANS: One should make sure that all the included objects are alsoserializable. If any of the objects is not serializable then it throws a
NotSerializableException.
16.What if I write static public void instead of public static void?
ANS: Program compiles and runs properly.
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17.What if the static modifier is removed from the signature of the
main method?
ANS: Program compiles. But at runtime throws an error
NoSuchMethodError.
18.What is the diff between RDO and ADO?
ANS: RDO is Hierarchy model whereas ADO is Object model. ADO can
access data from both flat files as well as the data bases. I.e., It is
encapsulation of DAO, RDO and OLE that is why we call it as OLE-DB
Technology.
19. Have you create Properties and Methods for your own Controls?
ANS: Properties Public variable of a Class & Method Public procedure of
a class.
20.How to change the Mouse Pointer?
ANS: Screen.MousePointer = VBHourGlass/VBNormal.
21.What if I do not provide the String array as the argument to the
method?
ANS: Program compiles but throws a runtime error
NoSuchMethodError.
22.What is the difference between Property Get, Set and Let?
ANS: Set Value is assigned to ActiveX Object from the form.
Let Value is retried to ActiveX Object from the form.
Get- Assigns the value of an expression to a variable or property.
23.How can one prove that the array is not null but empty?
ANS: Print args.length. It will print 0. That means it is empty. But if it
would have been null then it would have thrown a
NullPointerException on attempting to print args.length.
24.What are the Style properties of List Box?
ANS: Simple Single Select, Extended. Multiple Select.
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25.What environment variables do I need to set on my machine in
order to be able to run Java programs?
ANS: CLASSPATH and PATH are the two variables.
26.What is Collection Objects?
ANS: Similarly to arrays but is preferred over an array because of the
following reasons.
1. A collection objects uses less Memory than an array.
2. It provides methods to add and delete members.
3. It does not required reason statement when objects are added or
deleted.
4. It does not have boundary limitations.
27.Can an application have multiple classes having main method?
ANS: Yes it is possible. While starting the application we mention the
class name to be run. The JVM will look for the Main method only in the
class whose name you have mentioned. Hence there is not conflict
amongst the multiple classes having main method.
28.In project properties if we set Unattended what is it mean?
ANS: This cannot have user interface. This can be used for the COM
creation.
29. What are Checked and UnChecked Exception?
ANS: A checked exception is some subclass of Exception (or Exception
itself), excluding class RuntimeException and its subclasses. Making an
exception checked forces client programmers to deal with the
possibility that the exception will be thrown. e.g., IOException thrown
by java.io.FileInputStreams read () method.Checked exceptions are RuntimeException and any of its subclasses.
Class Error and its subclasses also are unchecked. With an unchecked
exception, however, the compiler doesnt force client programmers
either to catch the exception or declare it in a throws clause. In fact,
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client programmers may not even know that the exception could be
thrown. e.g., StringIndexOutOfBoundsException thrown by Strings
charAt () method Checked exceptions must be caught at compile time.
Runtime exceptions do not need to be. Errors often cannot be.
30.Handling Error in Calling chain.
ANS: This will call the top most error where the error is handled.
31.What is a Cartesian product in PL/SQL?
ANS: When a Join condition is not specified by the programmer or is
invalid (fails), PL/SQL forms a Cartesian product.
In a Cartesian product, all combinations of rows will be displayed.For example, All rows in the first table are joined to all rows in the
second table. It joins a bunch of rows and its result is rarely useful
unless you have a need to combine all rows from all tables.
32.Why we use Treeview Control?
ANS: To list the hierarchical list of the node objects. Such of files and
Directories.
33.What is the purpose of garbage collection in Java, and when is it
used?
ANS: The purpose of garbage collection is to identify and discard
objects that are no longer needed by a program so that their resources
can be reclaimed and reused. A Java object is subject to garbage
collection when it becomes unreachable to the program in which it is
used.
34.What is view Port?
ANS: The area under which the container provides the view of theActiveX Document is known as a view port.
35.What are the Style Properties of Combo Box?
ANS: Simple, Dropdown list We can type and select. Dropdown Combo
Only Drop Down.
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36.What is Mixed Cursors?
ANS: Static + Keyset.
37.What is HashMap and Map?
ANS: Map is Interface and Hashmap is class that implements that.
38.Describe synchronization in respect to multithreading?
ANS: With respect to multithreading, synchronization is the capability
to control the access of multiple threads to shared resources. Without
synchronization, it is possible for one thread to modify a shared
variable while another thread is in the process of using or updating
same shared variable. This usually leads to significant errors.
39.Difference between HashMap and HashTable?
ANS: The HashMap class is roughly equivalent to Hashtable, except that
it is unsynchronized and permits nulls. (HashMap allows null values as
key and value whereas Hashtable doesnt allow). HashMap does not
guarantee that the order of the map will remain constant over time.
HashMap is non-synchronized and Hashtable is synchronized.
40.Drag and Drop state numbers and functions?
ANS: State 0 Source control is being dragged with the range of a target.
1 Out of the range of a target.
2 One position in the target to another.
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