Removing duplicate characters in string preg_replace

Question

$value = "ABCC@CmCCCCm@CCmC@CDEF";

$clear = preg_replace('/@{1,}/', "", $value);

I need to remove duplicate @ and get something like:

ABCC@CmCCCCmCCmCCDEF (I need only first @)

How to do that?

strpos + substr_replace, no need to use regular expressions (especially if you cannot write one - it will be painful for you to maintain this code) — zerkms
– zerkms, Commented Nov 3, 2013 at 23:22
@zerkms: it can be a good way, you must only skip the first one. — Casimir et Hippolyte
– Casimir et Hippolyte, Commented Nov 3, 2013 at 23:24
@Casimir et Hippolyte: it can be, but as I said - it's always a good idea to always write a code you're able to maintain. Otherwise OP will be a frequent visitor here for every trivial change. And, no, I don't think it's a good way to learn. — zerkms
– zerkms, Commented Nov 3, 2013 at 23:26

Casimir et Hippolyte · Accepted Answer · 2013-11-03 23:54:38Z

4

A regex way:

$clear = preg_replace('~(?>@|\G(?<!^)[^@]*)\K@*~', '', $value);

details:

(?:           # open a non capturing group
    @         # literal @
  |           # OR
    \G(?<!^)  # contiguous to a precedent match, not at the start of the string
    [^@]*     # all characters except @, zero or more times
)\K           # close the group and reset the match from the result
@*            # zero or more literal @

edited Nov 3, 2013 at 23:54

answered Nov 3, 2013 at 23:45

Casimir et Hippolyte

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2 Comments

HamZa Over a year ago

Isn't that an atomic group ? Anyways +1000 :)

Casimir et Hippolyte Over a year ago

@HamZa: yes it is, and it can by replaced by (?:...) since it is useless with an alternation inside.

jerdiggity · Accepted Answer · 2013-11-03 23:39:11Z

3

Give this a try:

// The original string
$str = 'ABCC@CmCCCCm@CCmC@CDEF';
// Position of the first @ sign
$pos = strpos($str, '@');
// Left side of the first found @ sign
$str_sub_1 = substr($str, 0, $pos + 1);
// Right side of the first found @ sign
$str_sub_2 = substr($str, $pos);
// Replace all @ signs in the right side
$str_sub_2_repl = str_replace('@', '', $str_sub_2);
// Join the left and right sides again
$str_new = $str_sub_1 . $str_sub_2_repl;
echo $str_new;

answered Nov 3, 2013 at 23:39

jerdiggity

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