subtraction giving wrong answers

[cwoodman]

This simple bit of code gives ridiculous answers...

 

echo $Total;
echo "<br>";
echo $PrevTotal;
echo "<br>";
echo $Total-$PrevTotal;

 

Example output:

316
4,445
312

 

or

 

1,395
646
-645

 

Any idea why?

[Barand]

Numeric variables should not contain formatting characters such as commas. Same goes for values held in a db table.

4,100 is treated as 4 (only numeric digits up to the first non-numeric digit)

Format the numbers on output

Edited March 2, 2015 by Barand