Q1. How could Java classes direct program messages to the system console, but error messages, say to a file?

A. The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output could be re-directed:
Stream st = new Stream(new FileOutputStream("output.txt")); System.setErr(st); System.setOut(st);

*Q2. What's the difference between an interface and an abstract class?

A. An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implement multiple interfaces in your class.


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1.There is a game which is being played by 2 persons A and B. The 2 players start the game keeping identical 50 paise coins on a blank board alternately. The 50 paise coins can be kept in the board such that no part of the coin is outside the board. It can touch the board edge but cannot protrude outside the board. The two players can place the coins anywhere on the board. The coins placed during the course of the game can touch each other at the periphery but cannot overlap with the already placed coins.
The player who has space to place the last coin is the winner i.e the player placing the last coin on the board with no space available for the opponent is the winner. If you are one of the players, what will your strategy be so that you definitely win?
Answer:-
1. I shall keep the 1st coin the exact centre of the board.
2. now after each coin that he keeps, I shall keep a coin exactly diagonally opposite. This shall reduce the space for his further attempts more than any other strategy.

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51.Are the expressions *ptr++ and ++*ptr same?


Ans: No. *ptr++ increments the pointer and not the value pointed by it, whereas ++*ptr increments the value being pointed to

by ptr.



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1.What will be the output of the following code?
void main ()
{ 
   int i = 0 , a[3] ;
   a[i] = i++;
    printf (“%d",a[i]) ;
}
Ans: The output for the above code would be a garbage value. In the statement a[i] = i++; the value of the variable i would get assigned first to a[i] i.e. a[0] and then the value of i would get incremented by 1. Since a[i] i.e. a[1] has not been initialized, a[i] will have a garbage value.

2.Why doesn't the following code give the desired result?
int x = 3000, y = 2000 ;
long int z = x * y ;
Ans: Here the multiplication is carried out between two ints x and y, and the result that would overflow would be truncated before being assigned to the variable z of type long int. However, to get the correct output, we should use an explicit cast to force long arithmetic as shown below:

long int z = ( long int ) x * y ;
Note that ( long int )( x * y ) would not give the desired effect.


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