Answer:
The trigger code is given below
create trigger F1_Del
after delete on Friend
for each row
when exists (select * from Friend
where ID1 = Old.ID2 and ID2 = Old.ID1)
begin
delete from Friend
where (ID1 = Old.ID2 and ID2 = Old.ID1);
end
create trigger F1_Insert
after insert on Friend
for each row
when not exists (select * from Friend
where ID1 = New.ID2 and ID2 = New.ID1)
begin
insert into Friend values (New.ID2, New.ID1);
end
Answer:
No for GOTO
Yes for Pointer
Explanation:
<u>GOTO statement</u>
This declaration is used to pass control to the program's marked declaration. The label is the valid identifier and is positioned just before the declaration from which the control is transmitted.
It becomes hard to trace a program's control flow, making it hard to comprehend the program logic. Any program in C language can be written without using a GOTO statement.
<u>Pointers</u>
A C # pointer is nothing but a variable holding another type of memory address. However, in C # pointer only the memory address of the value types and arrays can be declared.
C # supports pointers to a restricted extent. Unlike reference kinds, the default trash collection system does not track pointer kinds. Pointers are not allowed to point to a type of structure containing a type of reference or a type of reference.
During the garbage collection process, the C #garbage collector can move objects in memory as they wish. The C #offers a unique fixed keyword for telling Garbage Collector not to move an item. This implies that the place of the value kinds referred to is fixed in memory. This is called pinning in C #.
Answer:
See explaination
Explanation:
StackExample.java
public class StackExample<T> {
private final static int DEFAULT_CAPACITY = 100;
private int top;
private T[] stack = (T[])(new Object[DEFAULT_CAPACITY]);
/**
* Returns a reference to the element at the top of this stack.
* The element is not removed from the stack.
* atreturn element on top of stack
* atthrows EmptyCollectionException if stack is empty
*/
public T peek() throws EmptyCollectionException
{
if (isEmpty())
throw new EmptyCollectionException("stack");
return stack[top-1];
}
/**
* Returns true if this stack is empty and false otherwise.
* atreturn true if this stack is empty
*/
public boolean isEmpty()
{
return top < 0;
}
}
//please replace "at" with the at symbol
Note:
peek() method will always pick the first element from stack. While calling peek() method when stack is empty then it will throw stack underflow error. Since peek() method will always look for first element ffrom stack there is no chance for overflow of stack. So overflow error checking is not required. In above program we handled underflow error in peek() method by checking whether stack is an empty or not.
Answer:
anyone could access something and hack others
Explanation:
