Thread: Can someone explain to me?

Can someone explain the coding in bold to me? I don't understand how to get 40 10 20 30.

public class Rotater {


public static void main(String[] args) {


int a = 10, b = 20, c = 30, d = 40;
int temp;

temp = d;
d = c;
c = b;
b = a;
a = temp;



System.out.println("before rotation: 10 20 30 40");
System.out.println("after rotation: " + a + " " + b + " " + c + " " + d);


}
}

Hello unleashed-my-freedom!
What is your question? You use the temp variable to rotate the values of your "basic" variables (a,b,c,d). So, you give every variable the value of the next (or previous) variable* . The additional variable (temp) is used for keeping the first basic variables's value and don't loose it.

*in your case next and previous don't have an actual meaning because the variables are not ordered but suppose they are (a-b-c-d)

Hope I was clear.

At first, I had 10 20 30 40
But the temp, I had 40 10 20 30.
So you mean if I use temp, the number will (in this case) increase by 1 position?

After the rotation the values have moved one step forward with the last value going to the first variable (like a cycle).

after initialization
a   b   c   d    temp
10  20  30  40      -
 
 
temp  = d;
a   b   c   d    temp
10  20  30  40      40
 
 
d = c;
a   b   c  d    temp
10  20  30  30   40
 
 
c = b;                   
a   b   c   d     temp
10  20  20  30      40
 
 
b = a;                 
a   b   c   d     temp
10  10  20  30      40
 
 
a = temp;           
a   b   c   d     temp
40  10  20  30      40

Hope this helps.

so we use temp just to increase the order by 1?

Originally Posted by unleashed-my-freedom

so we use temp just to increase the order by 1?

We use temp because otherwise you would loose a value. Think like you have two cups (A and B) in two positions (1 and 2 respectively) that each of them can place only one cup and you can carry only one cup in your hands. Now, if you want to exchange positions between cups you start like this:
take cup A and put it in position 1. But then you have to throw away cup B(because you can't have two cups in you a position or in your hands).
Therefore you need a new assisting position (3).
Then you put
1) cup A to position 3 - now position 1 is empty
2) cup B to position 1 - now position 2 is empty
3) cup A to position 2

So, temp is the assisting position.

Hope that makes sense.