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Index › Programming Questions & Help › Programs › Bizarre array behaviour
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Bizarre array behaviour (Read 594 times)
dunkster
Bizarre array behaviour
Apr 1st, 2007, 4:26pm  
Hi, as part of a program am I writing i set up a 2d array of values, however after setting the values they seem to be going missing. Here is the code in question;

Quote:
for (int z=0; z < numObj; z++) {
 
xtildeArray = new double[numObj][D];
 
xtilde = new double[numValues];
 
for (int i=0; i < D; i++){
   
xtilde[i] = d*objectsArray[z].getValue(i)/nhatdotx;
 
}
 
xtildeArray[z] = xtilde;

println(xtildeArray[z]);
}

println(xtildeArray[0]);


The first println statement within the loop displays the values intended correctly, however the second println outside the loop returns values 0,0,0 for whichever array element I call. The xtildeArray is declared globally, and im baffled as to what is going on. Any help would be greatly appreciated.

Andrew.
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fjen
Re: Bizarre array behaviour
Reply #1 - Apr 1st, 2007, 5:33pm  
that's because you are reassigning the array every loop. you have to move that before (outside) the for-loop:

Code:
  
xtildeArray = new double[numObj][D];
for (int z=0; z < numObj; z++)
{
  xtilde = new double[numValues];
  for (int i=0; i < D; i++)
  {
    xtilde[i] = d*objectsArray[z].getValue(i)/nhatdotx; 
  } 
  xtildeArray[z] = xtilde; 
  println(xtildeArray[z]); 
} 
println(xtildeArray[0]);


F
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dunkster
Re: Bizarre array behaviour
Reply #2 - Apr 1st, 2007, 5:38pm  
Thanks. Can't believe im making silly mistakes like this and not noticing. Cheers
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fjen
Re: Bizarre array behaviour
Reply #3 - Apr 1st, 2007, 5:47pm  
happens to me all the time, just spend 2 hours hunting for a bug. in the end turns out it was the first thing i wrote early this morning ... ouch.

F
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