array max num

Apodysophilia · 04-09-2003, 12:08 PM

omg, I feel so stupid

but,

Code:

     public int maxElt(int[] ary)
     {
          int asdf = 0;
          
          for( int aryIndex = 0; getSize() > aryIndex; aryIndex++) 
          { 
              if(ary[aryIndex] > ary[(aryIndex+1)])
              {
                         
                         asdf = ary[ ary[(aryIndex+1)] ];
             
               }
               else
               {
                         asdf = ary[aryIndex];
               }
          
          } 
          return asdf;
     }

the error message

Code:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException
        at TestAry.maxElt(TestAry.java:73)

i know whats wrong it is trying to get one more then the array is, But for the life of me i can't figure out what is wrong (i think i need to sleep more)if i figure it out 10min after i post this i gonna hate myself

any help would be aprecaded, the method is supposed to return the highest value in an int array

joe_bruin · 04-09-2003, 12:49 PM

ary[(aryIndex+1)]

this goes out of bounds when aryIndex is equal to (getSize() - 1)

abc123 · 04-09-2003, 02:17 PM

what is getSize() sposed to do? if you just want to loop through the array:

Code:

int ints[] = new int[100];
for(int i = 0; i < ints.length; i++){
   if(ints[i] == ....)
}

you won't get index out of bounds then.

Apodysophilia · 04-09-2003, 06:19 PM

Quote:

Originally posted by joe_bruin
ary[(aryIndex+1)]

this goes out of bounds when aryIndex is equal to (getSize() - 1)

i know that, that is what i am tryin to fix

Quote:

Originally posted by abc123
what is getSize() sposed to do? if you just want to loop through the array:

getSize() returns the number of used slots in the array, for example the person whants a 10int array but only fills it up to 6, i am trying to pick out the largest int value out of the arrray

saline · 04-09-2003, 08:08 PM

Ok I'm writing this on the assumption that you wrote getSize(). If this is so how are you holding empty spaces? Like if the array were empty (getSize() should return zero) then whats in the ten spaces? My thinking is that getSize() isn't doing what you think it's doing and it's always returning that every space is used so you're always going to the end of the array and then purposefully going one beyond with your code.

So assuming the array has ten slots getSize() is returning ten, aryIndex gets up to [9] (the tenth spot) and then inside your first if statment you're trying to access [10] the non-existant eleventh space of the array here:

(I'm essentailly saying here that joe_bruin was right but perhaps too brief in saying why)

Code:

   if(ary[aryIndex] > ary[(aryIndex+1)])
              {
                         
                         asdf = ary[ ary[(aryIndex+1)] ];
             
               }

Maybe I'm missing something significant here but thats my best guess for now.

I would suggest restructuring the whole algorithm where instead of comparing the present against the next value you compare the present against the past highest value.

Code:

int biggest(int[] ary)
{
  int cur_space;
  int largest = 0;
//this assumes the first space is the largest for no reason
//what-so-ever.

  for(cur_space = 0; cur_space < ary.length; cur_space++)
  {
    if(ary[cur_space] > ary[largest])
    {
      largest = cur_space;
    }
  }

return ary[largest];

}

If I've had a massive brain failure and this doesn't work or you don't get how it does or is supposed to work let me know.

Apodysophilia · 04-09-2003, 09:01 PM

saline your code work perfectly, thank you soo much, i now see what i was doing wrong, thank you once again:rock:

saline · 04-09-2003, 09:02 PM

And on that oh so wonderful note, I'm going to bed, rock rockity rock rock.

out of curiosity was I right about the getSize() thing or did you not check?

Apodysophilia · 04-09-2003, 09:08 PM

you where right about the getSize()

saline · 04-09-2003, 09:14 PM

I couldn't have been more right, thats awesome, I was like right squared. It's like I'm psychic, I'm like the John Edwards of debugging, reading functions that I can't even see.

Somebody stop me before my ego explodes...

Apodysophilia · 04-10-2003, 06:36 AM

Quote:

Originally posted by saline
I couldn't have been more right, thats awesome, I was like right squared. It's like I'm psychic, I'm like the John Edwards of debugging, reading functions that I can't even see.

Somebody stop me before my ego explodes...

lmao, i was reading this is the lab and i just started to laugh out loud for like 10min