php preg_replace array but only in the initial string

Question

This scripts

<?php
$pat = array ( '/A/', '/B/');
$rep = array ( 'B', 'C');
print preg_replace($pat, $rep, 'AAB');
?>

I would liket to print 'BBC' ('B' replaces 'A' and 'C' replaces only the initials 'B')

But it prints 'CCC' ('B' replaces 'A' and 'C' replaces 'B' and the 'A' previously replaced by 'B')

If I tried something like this script

<?php
$pat = array ( '/A/', '/B/');
$rep = array ( 'B', 'C');
print preg_replace($pat, $rep, 'AAB', 1);
?>

But it prints 'CAB'...

Thanks.

Bojan Kogoj · Accepted Answer · 2011-04-23 13:14:01Z

1

This should work :) You just change it's order, so it replaces B before A, and that's it

<?php
$pat = array ( '/B/', '/A/');
$rep = array ( 'C', 'B');
print preg_replace($pat, $rep, 'AAB');
?>

answered Apr 23, 2011 at 13:14

Bojan Kogoj

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Comments

NikiC · Accepted Answer · 2011-04-23 13:14:47Z

1

If that really is all you want (only replace single characters), just use strtr:

$str = strtr($str, 'AB', 'BC'); // means: replace A with B and replace B with C

If you are not talking just about single characters, but about strings (but still no regex), strtr will still work:

$str = strtr($str, array('Hallo' => 'World', 'World' => 'Hallo'));

answered Apr 23, 2011 at 13:07

NikiC

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I read strstr but it's strtr. That's the good answer! Thanks!

@nikic: What should be the answer if regex is required?