ARRAYS!!- Shift Down...

[Shivu]

yup, i'll just copy and paste then!

thanks a lot again!

[r691175002]

Ah, sorry I came back a little late.

The easiest solution is just to copy and paste the loop like you have done (Make sure you reuse the counter variable though if you think the teacher will count each one separately). If you absolutely have to use a single loop thats where the % operator comes into play:

code:

for (int i = 0; i < LOOP_TIMES*2; i++)     System.out.println (i % LOOP_TIMES);     // % Will wrap i around so that it is always within LOOP_TIMES     // 0 % 3 = 0     // 1 % 3 = 1     // 2 % 3 = 2     // 3 % 3 = 0 // Wrapped around     // 4 % 3 = 1     // 5 % 3 = 2     // 6 % 3 = 0 // Wrapped around again     // 7 % 3 = 1 ...

This will output 0 to LOOP_TIMES-1 twice.

Your code:

code:

for (int i=0; i<MAX; i++) {     temp1 = num [i];         temp2 = num [MAX-1];         num[i]=temp2;     num[MAX-1] = temp1; }

Becomes:

code:

for (int i=0; i<(MAX*2); i++) {     temp1 = num [i%MAX];         temp2 = num [MAX%MAX-1];         num[i%MAX]=temp2;     num[MAX%MAX-1] = temp1; }

(Untested, it may have a few off by one errors)

Picking up patterns like this is something that comes with time. I basically played around a bit and finally ended up with something that looked like it would work.

[Shivu]

hi! thanks for that....

but for the % operator, i'm a bit confused on what it does... meaning:

what does it mean to "wrap" i around?, does it reset i?

thanks

[jernst]

Shivu @ Sun Apr 20, 2008 2:45 pm wrote:

hi! thanks for that....

but for the % operator, i'm a bit confused on what it does... meaning:

what does it mean to "wrap" i around?, does it reset i?

thanks

Like the people above have said it gives a remainder from a divison. So it "wraps around" everytime the remainder returns to 0. For your example with 5 elements:

5 % 5 = 0
10 % 5 = 0
15 % 5 = 0

Similarly,
6 % 5 = 1
11 % 5 = 1 ..etc

So instead of trying to figure out when a counter should return back to zero to wrap the array back to the start you can use the modulo (%) to turn the 5 into a 0. I dont know if that made it any more clear or worse but I gave it a try

[Shivu]

no no that was great!

ok... so, regarding the code above (before the above post),

num [i%MAX]; the i%MAX makes sure that i stays less than MAX (which is 5 for example) ??

so like:

code:

for (int i=0; i<MAX*2; i++) { temp1 = num[i%MAX]; //the index # (of num) will be 0, then it'll be 1, then 2, then 3, then 4, then 5, and then again 0,1,2,3,4,5 =>that'll be when i will be less than MAX *2 (in this case 10).  so the loop will be run two times!? }

cuz if the condition would be i <MAX, then the loop would only run till i = 4...

oh!! i get it:) (or i think i get it...)

if someone could let me know if i'm understanding it properly, that'd be great! -lol

thanks a lot to everyone!!!!

[jernst]

Looks like you've got it