PHP Remove # using preg

Question

I need a regex to remove the # from a twitter name.

Tried this:

$name = '#mytwitter';
$str = preg_replace('/\#/', ' ', $name);

Sure this is a simple fix , but Google didn't help. Thanks!

score 6 · Accepted Answer · answered Mar 10 '11 at 17:19

6

You don't need to use preg_replace, just use str_replace:

str_replace('#','',$name);

answered Mar 10 '11 at 17:19

fredley

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score 2 · Answer 2 · answered Mar 10 '11 at 17:18

2

Why are you escaping #?

$name = '#mytwitter';
$str = preg_replace('/#/', ' ', $name);

Edit: Your original code does work, too. Note that preg_replace returns the substituted string but doesn't change the original. The value of $str is " mytwitter".

answered Mar 10 '11 at 17:18

Tim

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`preg_replace` is much slower than `str_replace`, there is no need to use it here – JamesHalsall Mar 10 '11 at 17:23
@Jaitsu: Certainly, but there is always a trade-off between fixing and rewriting the code. It is not obvious at all which the original poster would benefit the most from. – Tim Mar 10 '11 at 17:43

score 1 · Answer 3 · answered Mar 10 '11 at 17:20

1

You do not need to escape #.

$str = preg_replace('/#/', '', $name);

However, for a simple character removal, you are better off using str_replace(). It's faster for those situations.

$str = str_replace('#', '', $name);

answered Mar 10 '11 at 17:20

Andrew Moore

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score 1 · Answer 4 · edited May 23 '17 at 12:04

I would recommend using strtok for this, as it's more performant. Just use it like so:

$str = strtok('#mytwitter', '#');

Here are some benchmarks i just ran (50000 iterations):

strreplace execution time: 0.068472146987915 seconds
preg_replace execution time: 0.12657809257507 seconds
strtok execution time: 0.043070077896118 seconds

The script i used to benchmark is (taken from Beautiful way to remove GET-variables with PHP?):

<?php

$number_of_tests = 50000;

// str_replace
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$starttime = $mtime;

for($i = 0; $i < $number_of_tests; $i++){
    $str = "#mytwitter";
    $str = str_replace('#' , '', $str);
}
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$endtime = $mtime;
$totaltime = ($endtime - $starttime);
echo "strreplace execution time: ".$totaltime." seconds;  <br />";

// preg_replace
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$starttime = $mtime;

for($i = 0; $i < $number_of_tests; $i++){
    $str = "#mytwitter";
    $str = preg_replace('/#/', ' ', $str);
}
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$endtime = $mtime;
$totaltime = ($endtime - $starttime);
echo "preg_replace execution time: ".$totaltime." seconds;  <br />";

// strtok
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$starttime = $mtime;

for($i = 0; $i < $number_of_tests; $i++){
    $str = "#mytwitter";
    $str = strtok($str, "#");
}
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$endtime = $mtime;
$totaltime = ($endtime - $starttime);
echo "strtok execution time: ".$totaltime." seconds; <br />";

  [1]: http://php.net/strtok

thanks for this, will look into it, always handy to be able to speed things up! — BobFlemming, Mar 14 '11 at 09:40

PHP Remove # using preg

4 Answers4