# Doubt In Kathy& Bates book questions at page 198

vatsalya rao

Ranch Hand

Posts: 63

posted 9 years ago

The questions are as follows:

Class test{

public static void main(String arg[])

{

int x=0,y=0;

for(int z=0;z<5;z++)

{

if((++x>2)||(++y>2))

{

x++;

}

}

System.out.println(x + " " +y);

}

}

I traced it as follows

z=0- x=1,y=1;

z=1 x=2,y=2;

z=3 x=3 ,y=2 (Here x is >2 so x++ executed and now x is 4);

z=4 x=5 y=2(Here also x+ executed and x is 6 now)

So o/p should be x=6and y=2 but why it is mentioned in answers as

x=8 and y=2?

One more is

Class test{

public static void main(String arg[])

{

int x=0,y=0;

for(int z=0;z<5;z++)

{

if((++x>2)&&(++y>2))

{

x++;

}

}

System.out.println(x + " " +y);

}

}

I traced it as follows

z=0 x=1 y=0

z=1 x=2 y=0

z=2 x=3 y=1(the && condition is true so x++ evaluated and x is now 4)

z=3 x=5 y=2(here x++ excecuted and x is 6 now)

z=4 x=7 y=3

so o/p should be x=7 and y=3 right?

but it is mentioned as x=6 and y=3

where I go wrong?

Class test{

public static void main(String arg[])

{

int x=0,y=0;

for(int z=0;z<5;z++)

{

if((++x>2)||(++y>2))

{

x++;

}

}

System.out.println(x + " " +y);

}

}

I traced it as follows

z=0- x=1,y=1;

z=1 x=2,y=2;

z=3 x=3 ,y=2 (Here x is >2 so x++ executed and now x is 4);

z=4 x=5 y=2(Here also x+ executed and x is 6 now)

So o/p should be x=6and y=2 but why it is mentioned in answers as

x=8 and y=2?

One more is

Class test{

public static void main(String arg[])

{

int x=0,y=0;

for(int z=0;z<5;z++)

{

if((++x>2)&&(++y>2))

{

x++;

}

}

System.out.println(x + " " +y);

}

}

I traced it as follows

z=0 x=1 y=0

z=1 x=2 y=0

z=2 x=3 y=1(the && condition is true so x++ evaluated and x is now 4)

z=3 x=5 y=2(here x++ excecuted and x is 6 now)

z=4 x=7 y=3

so o/p should be x=7 and y=3 right?

but it is mentioned as x=6 and y=3

where I go wrong?

posted 9 years ago

Try adding some println statements to show what the code is doing. For example...

[ July 19, 2007: Message edited by: marc weber ]

[ July 19, 2007: Message edited by: marc weber ]

"We're kind of on the level of crossword puzzle writers... And no one ever goes to them and gives them an award." *~Joe Strummer*

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Shrikanth Nekkanti

Ranch Hand

Posts: 48

Les Hayden

Greenhorn

Posts: 28

posted 9 years ago

At z=2, you say that "&& condition is true", but the y>2 condition actually returns false for another two iterations of the loop. The if's block does not execute until z=4.

I traced it as follows

z=0 x=1 y=0

z=1 x=2 y=0

z=2 x=3 y=1(the && condition is true so x++ evaluated and x is now 4)

z=3 x=5 y=2(here x++ excecuted and x is 6 now)

z=4 x=7 y=3

so o/p should be x=7 and y=3 right?

but it is mentioned as x=6 and y=3

At z=2, you say that "&& condition is true", but the y>2 condition actually returns false for another two iterations of the loop. The if's block does not execute until z=4.

Les Hayden

vatsalya rao

Ranch Hand

Posts: 63

Israel Guerra

Greenhorn

Posts: 3

posted 9 years ago

Hail all!

It's a bit confusing this thing, but i got to the following conclusion:

z: 0 x: 1 y: 0 -> in the if condition, x is incremented

z: 1 x: 2 y: 0 -> again, the same thing

z: 2 x: 3 y: 1 -> x is incremented again, so the first part of the teste is true, making y also be incremented (just remembering here that y was not incremented before because && does not check the second statement if the first is false)

z: 3 x: 4 y: 2 -> same situation explained in the las step

z: 4 x: 6 y: 3 -> now we have the if scope executed so x is incremented 2 times.

Think its that!

Take care,

It's a bit confusing this thing, but i got to the following conclusion:

z: 0 x: 1 y: 0 -> in the if condition, x is incremented

z: 1 x: 2 y: 0 -> again, the same thing

z: 2 x: 3 y: 1 -> x is incremented again, so the first part of the teste is true, making y also be incremented (just remembering here that y was not incremented before because && does not check the second statement if the first is false)

z: 3 x: 4 y: 2 -> same situation explained in the las step

z: 4 x: 6 y: 3 -> now we have the if scope executed so x is incremented 2 times.

Think its that!

Take care,

--<br />Guerra