greater than or equal too error

[yume]

Hi,
I need some help for a seemingly simple problem.

For some reason (probably stupidity but hey) i can't get <= to evaluate correctly.

my code caluclates a percent difference which calculates fine.

however if the percent difference is equal to -10 the score should be 50 points, instead I keep getting 20 points.....

here is the if statement
if($percentdiff<=-20){
$market=70;
}elseif($percentdiff<=(-10) && $percentdiff>-20){
$market=50;
}elseif($percentdiff>-10 && $percentdiff<10){
$market=20;
}elseif($percentdiff>=10){
$market=0;
}

I have played around with brackets and || and && and other stuff but can't get it to evaluate correctly!?

Any expert insight will be greatly appreciated!

Cheers,
Yume

[leatherback]

Try this:

if($percentdiff<=-20)
  { 
  $market=70; 
  }
  elseif($percentdiff<=-10)
  { 
  $market=50; 
  }
  elseif($percentdiff<=10)
  { 
  $market=20; 
  }
  else
  {  

  $market=0; 
  } 

[yume]

thanks leatherback,
your code is a whole lot nicer - however it still returns 20 for the answer !?

😕

[Weedpacket]

You sure $percentdiff is 10 and not something like 10.0000000000000001 (which looks like "10" when you display it)? Every time you use the division operator, the result is a floating point number, which might lose accuracy. Try rounding the percentage off.

[yume]

weedpacket,
yes it is -10 .... exactly 🙁

its calculated as follows

$percentdiff = (($lastyear - $thisyear)/ $lastyear) * 100

i noticed this problem when the following values where used.
$lastyear = 1.0
$thisyear = 0.9

[tekky]

if($percentdiff<=10) 
  {  

  $market=20;  

  } 
  elseif($percentdiff<=-10) 
  {  

  $market=50;  

  } 
  elseif($percentdiff<=-20) 
  {  

  $market=70;  

  } 
  else 
  {   

  $market=0;  

  }

try that...?

maybe PHP has some screwed up deal with negatives like MS EXCEL (hopefully thats not the case....)

[edit -- worst case, you may need to use int($percentdiff) on your checks... --]

[yume]

tekky,
yes I tried leatherback's code changes and got the same problem.

maybe PHP has some screwed up deal with negatives like MS EXCEL

thats what i was thinking .... but haven't come across any info on this problem, and if it was a negative no. / php thing i imagine there would be something about it somewhere on the net .....

i will have a look at int as you suggest .... thanks.

[yume]

i expanded the code to look like this ....

if($percentdiff<-20){
  $market=70;
}elseif($percentdiff==-20){
  $market=70;
}elseif($percentdiff<-10){
  $market=50;
}elseif($percentdiff==-10){
  $market=50;
}elseif($percentdiff<10){
  $market=20;
}elseif($percentdiff==10){
  $market=0;
}elseif($percentdiff>10){
  $market=0;
}else{
  $market=0;
}

i tried tekky's suggestion by converting $percentdiff using intval($percentdiff) before the if statment.

NOW
i have found that when
$thisyear = 90;
$lastyear = 100;
then the percent difference is -10 and I get the correct answer ($market=50) the result from intval is -10.

however I am still having the same problem when
$thisyear = 0.9;
$lastyear = 1;
and intval evaluates to -9 ?! ... which doesn't make sense (to me anyway)

so i think i have some kind of variable / rounding problem .... but what (& how to fix it) ..... I'm not sure

😕