Fastest method of splitting string into an array in PHP

Question

I have a PHP script which splits strings into arrays using prey_split. The preg_split code is:

preg_split("~(?<!\*):~", $val);

Which essentially splits the string where there is a colon, without a preceding asterisk. For example: "h*:el:lo" turns into array("h*:el", "lo")

This process is quite resource intensive and slow when splitting large amounts of strings. Is there a faster method to achieve this?

Im afraid there won't be a faster alternate to using a regular expression, because of that condition that before colon there should not be an *. Otherwise you could try explode and compare the results — Hanky Panky
– Hanky Panky, Commented Mar 19, 2013 at 11:50
only other way I can think of is to loop over the string yourself and manually build the array, but it's probably slower than using preg. — Marc B
– Marc B, Commented Mar 19, 2013 at 11:51
@bhumi: in general, yes, but explode doesn't support regexes, and does a blind split. OP wants *: excluded from split points. — Marc B
– Marc B, Commented Mar 19, 2013 at 11:52
@MarcB - I can confirm than string looping is like 10 times slower. — Álvaro González
– Álvaro González, Commented Mar 19, 2013 at 12:07

Álvaro González · Accepted Answer · 2013-03-19 12:42:55Z

1

You could try something like this:

$string = "h*:el:lo";
$string = str_replace("*:", "#", $string);
$array = explode(":", $string);

I'm not sure of what the speed will be like., but once you remove the *: bits form the string, its simple to explode. Perhaps you can put the *: back in after the operation if you need it.

edited Mar 19, 2013 at 12:42

Álvaro González

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answered Mar 19, 2013 at 11:54

Husman

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7 Comments

Álvaro González Over a year ago

I haven't tested thoroughly but getting the *: back seems to be very slow, even with array_map().

Husman Over a year ago

Perhaps its not needed, unless its for display purposes. I have had an idea, watch the edit on my post shortly.

Husman Over a year ago

Now theres no need to put the *: back in. We leave them in place prior to the split.

Álvaro González Over a year ago

Now your code is faster because it no longer follows the spec.

Husman Over a year ago

How are you testing the timing of the script?

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Alan Moore · Accepted Answer · 2013-03-19 12:54:29Z

0

Are you required to use preg_split()? Because it's easier to use preg_match_all():

preg_match_all('/(?:^|:)([^*:]+(?:\*.[^*:]+)*)/', $subject, $result, PREG_PATTERN_ORDER);
$result = $result[1];

answered Mar 19, 2013 at 12:54

Alan Moore

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