Archive for the ‘Uncategorized’ Category

Suppressing errors in PHP with control operator @

Wednesday, December 7th, 2011

Errors give valuable information, it’s worth paying attention to.

Sometimes though when parsing content from different sources you can run into errors you can prevent, or you can’t solve.

Reading something into simpleXML that isn’t 100% validated XML, because it’s encoded in ISO-8859 instead of UTF-8.

Then use the PHP one error control operator @.

When prepended to an expression in PHP, any error messages that might be generated by that expression will be ignored.

Tha comes quite in hand in the following piece of code :


$xml = @simplexml_load_file('rssfeed.xml');

No more errors.

Posted in Uncategorized | No Comments »

Creating csv content

Friday, February 25th, 2011

It is tempting to simply generate CSV data with writing comma-separated  array-values.

implode(",", $data_array);

Unfortunately this obvious way of doing turns out to be a bad idea. Often it seems to be working at first, but eventually you’ll be faced with annoying bugs, wrongly escaped data.

Fortunately, PHP has a native function to write CSV values to a file. 

fputcsv()

With a little trick you can use this function to write values to the screen.
Use the built-in streamwrappers:

 $outstream = fopen("php://output", 'w');
 fputcsv($outstream, $data_array, ',', '"');
 fclose($outstream);

This will echo the data to the screen.
Most people won’t know `php://output`. A pity it’s really powerful.

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PHP memory leak

Wednesday, November 28th, 2007

Consider an RSS feed read in as an SimpleXMLobject $rss.

What’s the difference between:

foreach ($rss->channel as $channel) {
...
}

and
$foo = $rss->channel;
foreach ($foo as $channel) {
...
}

Not much you would say, the first code example is shorter and more to the point. However when putting the scripts to work, (with a big rss file) we’ll soon see the difference.

Memory problem and a growing swap file

After a while the former example is causing a lot of disk activity and you will see your swap file grow and grow, at my computer it reached the maximum of 4 GB and off course it took ages for the script to finish.

And all that while the maximum memory usage for a script is set to 24MB in php.ini. Should run in a 1G computer you would say.
Well example 2 does but example 1 does not!

Is seems that iterating over an object-property in a foreach loop is troubled by a memory leak.

Solution

Example 2 is the workaround!

Conclusion

PHP 5.1 until 5.2 seem to suffer from this memory leak.

Posted in PHP, Uncategorized | 10 Comments »

Technorati Post

Wednesday, December 20th, 2006

Technorati Profile
No further use. :)

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