Two files, exactly the same code, different output?

Question

This is the weirdest thing that has ever happened to me since I am a (PHP) programmer...

I have two files, with the following code (proj. euler stuff) that return different outputs.

<?php
$numbers =<<<eot
2,3
5,2
9,3
4,9
6,3
10,5
eot;
$numbers = explode("\n",$numbers);
$max = 0;
foreach($numbers as $k => $n){
    list($base,$expo) = explode(',',$n);
    $theLog = log($base,10);
    $result = bcmul($theLog,$expo,10);

    if(bccomp($result,$max,10) == 1){
        echo '<br/>max so far is ' . $result . ' for base ' . $base . '[log:'.$theLog.'] and exponent ' . $expo ;
        $max = $result;
    }
}
echo '<pre>';
print_r($numbers);
echo '</pre>';
echo $max;

FILE1, euler.php // outputs as expected:

max so far is 0.9030899869 for base 2[log:0.30102999566398] and exponent 3
max so far is 1.3979400086 for base 5[log:0.69897000433602] and exponent 2
max so far is 2.8627275283 for base 9[log:0.95424250943932] and exponent 3
max so far is 5.4185399219 for base 4[log:0.60205999132796] and exponent 9

5.4185399219

FILE2, euler2.php // bogus output:

max so far is 5 for base 10[log:1] and exponent 5

5

Can anyone think of a valid reason for this to happen?

I've tested it and I can tell that in euler2.php, the bogus one, $result = bcmul($theLog,$expo,10); doesn't like $theLog being a float value, therefore bcmul(0,$expo) = 0. $theLog, however, holds the right value.

Why would bc functions behaviour change from one file to the other?

NOTE: There is no bcscale set in any of the files, and if I set it to bcscale(10); the result is exactly the same.

Does anything change if you specify the values as an array instead of a text block? — Pekka, Jul 22 '10 at 11:25
are you really sure the two files are the same? Did you make a diff? If Yes: Are they running on the same system? — jigfox, Jul 22 '10 at 11:26
@Pekka: After knowing the issue I can tell you that it would work to have an array instead of the heredoc, however in the real case, there are hundreds of values and was not an option. Thanks ---------------------------- @Jens: Both files were running at the same system. I didn't do any diff... I would have found the problem if I did. My bad... But given the circumstances I was miles from doing it... Thanks — acm, Jul 22 '10 at 13:22

score 3 · Accepted Answer · answered Jul 22 '10 at 11:32

3

You have different EOL characters in your files. I can repro your error with Windows EOL (\r\n) and correct behaviour with Unix EOL (\n).

answered Jul 22 '10 at 11:32

SilentGhost

307,395
66
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that's exactly the issue... one file has `\r` while other has `\n`... I don't know why though, same editor being used for both files and code was copy pasted from the one working to the other... – acm Jul 22 '10 at 12:55

score 2 · Answer 2 · answered Jul 22 '10 at 11:34

2

Sometimes when files look identical, they can have different encodings or line-endings.

Can't say why that would affect your result though.

Try diffing them (eg. using WinMerge)

Using Notepad++ you can easily edit the encoding and/or line-endings, via the Format menu.

answered Jul 22 '10 at 11:34

g t

7,287
7
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I was using notepad++ and copy/pasted code from one file to the other however, that's the issue... EOL are different therefore `explode("\n")` will work in first file while `explode("\r")` will work in second file... thanks :) – acm Jul 22 '10 at 12:56

Two files, exactly the same code, different output?

2 Answers2