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# Positive or Negative value returned from comparison

Posted on 2008-10-01
Medium Priority
896 Views
Hello,

This should be a quick fix for almost anyone :) but i have never had to deal  with absolute value or a comparison of this type before.
Below is the code i am currently using. Now what i am trying to accomplish is this.

I have a current count and a previous count. Both values are correct coming into the function.

I want to compare the 2 values and find the difference, Either positive or negative or equal etc.

Now if the value is positive i want to output a +(number) if it's negative i want to output -(number)

I thought in theory this would work. However i always seem to evaluate to a positive number.

Perhaps someone can help me out and tell me where i messed up

Thanks for the help.

``````function FindVariance(\$Previous,\$Current)
{
if ( is_numeric(\$Current) && is_numeric(\$Previous) ) {
\$Difference = abs( \$Current - \$Previous );
}

if(Difference > \$Current)
{
\$this->CountChange = "-".\$Difference;
}
elseif(\$Difference < \$Current )
{
\$this->CountChange = "+".\$Difference;
}
else if(!is_numeric(\$Difference))
{
\$this->CountChange=null;
}
else
{
\$this->CountChange = \$Difference;
}

return \$this->CountChange;
}
``````
0
Question by:Defunct-Exodus
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• 3

LVL 4

Expert Comment

ID: 22617419
missing a space on the 2nd else if?
0

LVL 4

Expert Comment

ID: 22617423
err, make that the 1st one
0

Author Comment

ID: 22617697
Sorry i edited the code a bit before i posted it, The syntax etc appears to be correctly on my end.

But for some reason it never shows a "-" just a "+" even if the value is lower.
0

LVL 4

Expert Comment

ID: 22618474
Can you post your current syntax, cause I'm still seeing errors
0

Author Comment

ID: 22618587
Okay here you go,

Hopefully it is something as simple as a syntax error on my part lol.
``````	function FindVariance(\$PreviousCount,\$CurrentCount)
{
if ( is_numeric(\$CurrentCount) && is_numeric(\$PreviousCount) ) {
\$Difference = abs( \$CurrentCount - \$PreviousCount );
}

if(\$Difference > \$CurrentCount)
{
\$this->CountChange = "-".\$Difference;
}
elseif(\$Difference < \$CurrentCount)
{
\$this->CountChange = "+".\$Difference;
}
else if(!is_numeric(\$Difference))
{
\$this->CountChange=null;
}
else
{
\$this->CountChange = \$Difference;
}

return \$this->CountChange;
}
``````
0

LVL 4

Expert Comment

ID: 22619468
As far as I can tell, what I have should work.
``````       function FindVariance(\$PreviousCount,\$CurrentCount)
{
if ( is_numeric(\$CurrentCount) && is_numeric(\$PreviousCount) ) {
\$Difference = abs( \$CurrentCount - \$PreviousCount );
}

if(\$Difference > \$CurrentCount)
{
\$this->CountChange = "-".\$Difference;
}
else if(\$Difference < \$CurrentCount)
{
\$this->CountChange = "+".\$Difference;
}
else if(!is_numeric(\$Difference))
{
\$this->CountChange=null;
}
else
{
\$this->CountChange = \$Difference;
}

return \$this->CountChange;
}
``````
0

LVL 4

Expert Comment

ID: 22619513
Another quick question. Where are you getting the numbers for previouscount and currentcount? Unless  previouscount is double the value of currentcount, your number will always return positive due to the fact that you are using absolute value.
0

LVL 4

Expert Comment

ID: 22619704

``````       function FindVariance(\$PreviousCount,\$CurrentCount)
{
if ( is_numeric(\$CurrentCount) && is_numeric(\$PreviousCount) ) {
\$Difference = abs( \$CurrentCount - \$PreviousCount );
}

if(\$Difference < \$CurrentCount)
{
\$this->CountChange = "-".\$Difference;
}
else if(\$Difference > \$CurrentCount)
{
\$this->CountChange = "+".\$Difference;
}
else if(!is_numeric(\$Difference))
{
\$this->CountChange=null;
}
else
{
\$this->CountChange = \$Difference;
}

return \$this->CountChange;
}
``````
0

LVL 4

Accepted Solution

Jerrod_W earned 2000 total points
ID: 22619836
My php is pretty rusty, but I think will work better towards what you are trying to do. I'm kinda tired, so ignore my other junk.
``````       function FindVariance(\$PreviousCount,\$CurrentCount)
{
if ( is_numeric(\$CurrentCount) && is_numeric(\$PreviousCount) ) {
\$Difference = ( \$CurrentCount - \$PreviousCount );
}

if(\$Difference < \$CurrentCount)
{
\$this->CountChange = "-".\$Difference;
}
else if( \$Difference  < 0)
{
\$this->CountChange = "+".abs ( \$Difference );
}
else if(!is_numeric(\$Difference))
{
\$this->CountChange=null;
}
else
{
\$this->CountChange = \$Difference;
}

return \$this->CountChange;
}
``````
0

Author Closing Comment

ID: 31502105
Well that was it, I totally messed up using abs, I should have just tried to keep things simple.

Jerrod, Thank you very much for your help.
0

LVL 4

Expert Comment

ID: 22625175
You may also want to add something to check when the currentcount is less than or equal to zero. You will have some weird things happen if you don't.
0

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