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Reading a specific line in a file


6th April 2008, 669 views

After reading something on the php-general list I decided that a) I'm bored, and b) I'll write something which handles it. So here it is. It's very simple when it comes down to it, but does incorporate a line cache so that if you're constantly jumping around large files reading the same line then this should help speed things up slightly.

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Comments

Author: Brian Holub
Posted: 6th April 2008 18:53
Just curious if there was a performance reason why you chose the following:

/**
* Check the line cache first
*/
if ($this->useCache AND isset($this->cache[$number])) {
return $this->cache[$number];
}

instead of using the $this->isCached($number)?

Thanks,
Brian
Quote
Author: Richard Heyes
Posted: 6th April 2008 19:33
Brian Holub:
> Just curious if there was a performance reason
> why you chose the following:
>
> ...

Not really - I probably just wrote the isCached method after I wrote that bit.
Quote
Author: Greg
Posted: 7th April 2008 00:59
Or, SPLFileObject?

$file = new SPLFileObject($filename);

$file->seek(12);

$line = $file->getCurrentLine();
Quote
Author: Hasin
Posted: 7th April 2008 19:35
Greg, you took my bread away, heh heh. I just wrote almost the same code using SplFileObject, came to post as a comment and saw that you've already done it. Here is what I wrote


$linereader= new SplFileObject("/path/to/your/file");

$linenumber = 16;

$linereader->seek($linenumber);
$line = $linereader->current();
echo $line;
Quote
Author: Richard Quadling
Posted: 8th April 2008 16:23
If you have said not to cache, the cache is still updated.

I suppose if you are wasting cpu cycles NOT caching, then by storing the data in the cache (and never using it) is in the same vein.

$this->cache[$number] = $line;

should be ...

if ($this->useCache) {
$this->cache[$number] = $line;
}

But only if you care enough.

Regards,

Richard "Not Richard" Quadling.
Quote

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