Using preg_replace to replace string inside

Question

<?php

$str = htmlspecialchars('<nav><a>something</a></nav>');

$pattern = htmlspecialchars('/<nav><a>something</a></nav>/i');

echo htmlspecialchars(preg_replace($pattern, '<nav> <a href="hi">click</a> 

</nav>', $str));

?>

I need PHP to echo like this:

<nav> <a href="hi">click</a> </nav>

But it's showing this error:

Warning: preg_replace() expects parameter 4 to be int, string given in /opt/lampp/htdocs/Workaera/Sample.php on line 19

There is no pattern in $pattern. Try stripos() instead of preg_replace. — Syscall
– Syscall, Commented Feb 4, 2021 at 7:37
<nav><a>something</a></nav> this is the required pattern mentioned, — Adwaith
– Adwaith, Commented Feb 4, 2021 at 7:46

nikserg · Accepted Answer · 2021-02-04 08:02:05Z

1

You forgot to escape slashes. This code works:

$str = htmlspecialchars('<nav><a>something</a></nav>');

$pattern = htmlspecialchars('/<nav><a>something<\/a><\/nav>/i');

echo htmlspecialchars(preg_replace($pattern, '<nav> <a href="hi">click</a> 

</nav>', $str));

?>

But in your case preg_replace is probably overkill. Try just str_replace instead:

$str = htmlspecialchars('<nav><a>something</a></nav>');

$pattern = htmlspecialchars('<nav><a>something</a></nav>');

echo str_replace($str, $pattern, '<nav> <a href="hi">click</a> 

</nav>', $str);

answered Feb 4, 2021 at 8:02

nikserg

3821 silver badge12 bronze badges

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

1 Comment

Syscall Over a year ago

Right. But OP have a /i modifier. Maybe use str_ireplace() instead.

Cray · Accepted Answer · 2021-02-04 08:03:52Z

0

Your pattern is not valid, because of the unescaped forward slashes in HTML closing tags.

What you should be doing is something like

//escape HTML
$htmlEscapedPattern = htmlspecialchars('<nav><a>something</a></nav>');
//escape slashes
$forwardSlashEscapedPattern = str_replace("/", "\/", $htmlEscapedPattern);
//wrap as regex pattern
$pattern = "/" . $forwardSlashEscapedPattern . "/i";

answered Feb 4, 2021 at 8:03

Cray

2,8468 gold badges25 silver badges34 bronze badges

1 Comment

Cray Over a year ago

You should provide more information then, as this snippet returns the exact result you are expecting. Also note that in your original code you are printing escaped HTML with htmlspecialchars, but in the expected output the HTML is not escaped. If that is the problem just echo without escaping, e.g echo preg_replace($pattern, '<nav> <a href="hi">click</a> </nav>', $str);

John Doe · Accepted Answer · 2021-02-04 08:08:19Z

0

use the following php code to get your desired result.

$str = htmlspecialchars('<nav><a>something</a></nav>');
$pattern = htmlspecialchars('/<nav><a>something<\/a><\/nav>/i');
echo htmlspecialchars(preg_replace($pattern, '<nav> <a href="hi">click</a> </nav>', $str));

answered Feb 4, 2021 at 8:08

John Doe

1,4341 gold badge6 silver badges14 bronze badges

Collectives™ on Stack Overflow

Using preg_replace to replace string inside

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related