Using preg_replace to replace only first match

Question

I am testing the str_replace in phpList and I want to replace the first match of a string. I found on other posts that I should use preg_replace if I want to replace the first match of a string, the problem is preg_replace does not return a string for some reason.

Both

$fp = fopen('/var/www/data.txt', 'w');
$string_test = preg_replace(basename($html_images[$i]), "cid:$cid", $this->Body,1);
fwrite($fp,$string_test);
fclose($fp);

and

$fp = fopen('/var/www/data.txt', 'w');
fwrite($fp,preg_replace(basename($html_images[$i]), "cid:$cid", $this->Body,1));
fclose($fp);

writes an empty string to the file. I would like to know how to get a return string and str_replace does not seem to work with first match. However, str_replace would return a string.

preg_replace accepts a regular expression as first parameter. — xdazz
– xdazz, Commented Mar 17, 2014 at 5:31
possible duplicate of Replace string only once with php preg_replace — Ja͢ck
– Ja͢ck, Commented Mar 17, 2014 at 5:46

Itay Grudev · Accepted Answer · 2014-03-17 05:36:00Z

0

preg_replace()'s does a Regular Expression match and replace. You are passing it a string instead of a valid RegEx as the first argument.

Instead you might be looking for str_replace() which does string replacement.

answered Mar 17, 2014 at 5:36

Itay Grudev

7,5544 gold badges60 silver badges97 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

user1352777 Over a year ago

I will look into Regular Expression. I tried this fwrite($fp,str_replace(basename($html_images[$i]), "cid:$cid", $this->Body,1)); with str_replace, it does not seem to work.

2 revs · Accepted Answer · 2014-03-17 05:46:15Z

0

Actually, preg_replace() is the wrong tool if you just want to perform a regular find & replace operation. You could perform a single replacement using strpos() and substr_replace() for instance:

$find = basename($html_images[$i]);
$string_test = $this->Body;
if (($pos = strpos($string_test, $find)) !== false) {
    $string_test = substr_replace($string_test, "cid:$cid", $pos, strlen($find));
}

With preg_replace() you would get something like this:

$string_test = preg_replace('~' . preg_quote(basename($html_images[$i], '~') . '~', "cid:$cid", $this->Body, 1);

For convenience, you can wrap either two into a function called str_replace_first().

edited Mar 17, 2014 at 5:46

community wiki

2 revs
Jack

Collectives™ on Stack Overflow

Using preg_replace to replace only first match

2 Answers 2

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related