Swap two numbers without using a temporary variable

[PcEnthu]

Ok guys. Here is the problem. There are two variables x and y which hold numbers. You have to swap the value of the two variables. U might say, just store the value of x in a temporary variable z, store value of y in x and finally store z value in y Here is the tricky part, u have to do it without using the variable z

[mediator]

x=a
y=b
x=x+y
y=x-y
x=x-y

show x,y

[Kalyan]

x,y be the nos.

1) x=x+y
2) y=x-y
3) x=x-y

u got them swapped.

[VINSTAR]

x=x+y
y=x-y
x=x-y

[ray|raven]

You can even use division and multiplication operators.

x=x*y
y=x/y
x=x/y

[PcEnthu]

@ all u guys, That was fast and u got that cracked that easily. Well done. I will try to come up with some level up questions later.

[QwertyManiac]

Or if you wish to do it the l33t way, use XOR.

Starting with x=10, y=20

x^=y
y^=x
x^=y

Now x=20 and y=10.
Logic's the same as addition mostly, except its bitwise.

Edit: This a challenge or a homework question? For challenges, there exists a thread, I hope you can revive it with better questions than the ones already present.

[blueshift]

// 'a' and 'b' are the two variables.

a=a^b
b=a^b
a=a^b

[PcEnthu]

Originally Posted by rayraven

You can even use division and multiplication operators.

x=x*y
y=x/y
x=x/y

That would work for positive and negative numbers and not for zero

[ray|raven]

^Yep. Thats one limitation, by using div.

[Jove]

yeah...XORing is much better as compared to other suggested methods(here).
Other methods may not work if we are dealing with MAX possibles values of respective data types which results in overflow..so,
if(a!=b) ///if a==b, no need of swapping values
a^=b^=a^=b;
swaps the values in a and b

cheers

[Desi-Tek.com]

x = 2
y = 4

y = y-x = 2
x = y+y = 4

[ray|raven]

Originally Posted by Desi-Tek.com

x = 2
y = 4

x = y-x = 2
y = x+x = 4

Lolz, that works only for those no's i guess.

Try these,
x=5
y=7

x = y-x = 7-5 = 2 ?
y = x+x = 2+2 = 4 ?

Crappy logic.

[hariharan]

i can do that in a single statement.. swap two number in w/o temp var


x ^= y ^= x ^= y;


This swaps the two varaibles... OF course in c and other languages which support bit wise operators..!!

[QwertyManiac]

@rayraven - Lol! By the way, D-Tek.com and Dheeraj are one and the same I think.

Originally Posted by Desi-Tek.com

x = 2
y = 4

x = y-x = 2
y = x+x = 4

Hahah, moreover you started with x=2 and y=4 and ended with the same

[ray|raven]

^Lolz, i missed that part
What was he thinking while writing it?

I've known guys who try to deduce logic from examples.
Crappy way, if you ask me. 99% of the time you end up with a logic that works only for the example.

[Desi-Tek.com]

oh sorry i am awake from 24 hour

public
class Swap{
staticvoid swap(int x,int y){
//int temp=x;
x^=y; //2
y^=x; // 5
x^=y; //7
System.out.println("After swapping x = " + x + " y = " + y);
}
publicstaticvoid main(String[] args){
int x=5;
int y=7;

System.out.println("Before swapping x="+x+" y="+y);
swap(x,y);

}

}

//one line logic

public class Swap{
static void swap(int x,int y){
y=(x+y)-(x=y);
System.out.println("After swapping x= " + x + " y = " + y);
}
public static void main(String[] args){
int x=5;
int y=7;

System.out.println("Before swapping x="+x+" y="+y);
swap(x,y);

}
}

[aditya.shevade]

LOL this has been discussed before....

anther way apart from the XOR way is,

b = a + b - (a = b); you are done.

[eggman]

Originally Posted by Desi-Tek.com

x = 2
y = 4

x = y-x = 2
y = x+x = 4

Ha ha ha ha ha ha ha ha ha ha ha ha ha ha

I've never seen a post funnier and noobier than this!!!!!

[mehulved]

Originally Posted by eggman

Ha ha ha ha ha ha ha ha ha ha ha ha ha ha

I've never seen a post funnier and noobier than this!!!!!

I have.

[aditya.shevade]

Oi mehul.... he said he has not... he did not say you have not....

[Zeeshan Quireshi]

In Ruby:

b,a = a,b

[ray|raven]

Originally Posted by aditya.shevade

Oi mehul.... he said he has not... he did not say you have not....

Sarcasm perhaps?

[aditya.shevade]

^^ yeah... I guess

Was it Mehul?

[Vivek788]

well u can use these in a loop or condition statement like the if or for to avoid a semicolon.