Comparing decimal numbers in php

[gevensen]

I am comparing 2 decimal numbers I am pulling from a mysql file

for ex

$row[0]==$row1[0]

every once in a while i get a bad positive when I do

if($row[0]==$row1[0]) when they are exactly the same?

 

One query is a SELECT amount FROM table

 

the other is a select SUM(amount) FROM table2

 

any ideas why?

 

ive tried making them both abs()

 

when I print the out they are =

 

 

[scootstah]

A couple good answers here for why this occurs.

[smerny]

and how to work around it:

 

 

http://www.php.net/manual/en/language.types.float.php

$a and $b are equal to 5 digits of precision.

<?php
$a = 1.23456789;
$b = 1.23456780;
$epsilon = 0.00001;

if(abs($a-$b) < $epsilon) {
    echo "true";
}
?>

[gevensen]

ok yesterday i wrapped the decimal values like this, numbers are an example

<?php
$decimal1=2.50;
$decimal2=2.50;
if(strval($decimal1)!=strval($decimal2))(
blah blah blah
}
?>

 

that worked

 

if i am understanding the eplison thing i could also

 

<?php
$decimal1=2.50;
$decimal2=2.50;
$epsilon = 0.00001;

if(abs($decimal1-$decimal2) < $epsilon) {
    echo "true";
}
?>

 

correct??

 

 

[gevensen]

sorry dumb question i tried it and it works thanks!