We help IT Professionals succeed at work.

We've partnered with Certified Experts, Carl Webster and Richard Faulkner, to bring you two Citrix podcasts. Learn about 2020 trends and get answers to your biggest Citrix questions!Listen Now


Function to replace first occurence only.

Coolkill asked
Medium Priority
Last Modified: 2010-05-16

I'm after a function to replace the first occurance of string only, with a replacement string..

basically ,str_replace but only for the first occurance, not all..

Anyone up for it?
Watch Question

Top Expert 2006

When your php version is right, you can use a 4th parameter to str_replace:

$string = str_replace($old,$new,$string,1);

Otherwise, try this quick and dirty one:

$string = implode('newstring', explode('occurance', $string, 2));

Or the method for optimum customisation and backwards compatibility (this works in PHP 4 and above):
$string = preg_replace($pattern, $replace, $string, 1);

Look at the php manual: http://php.net/manual

Not the solution you were looking for? Getting a personalized solution is easy.

Ask the Experts
Richard QuadlingSenior Software Developer

Roonaan is not correct.

The 4th parameter is used to return the number of times it was replaced, not to control how many times it was replaced. Notice the & in the function definition. This is an output property, not an input property. Though I DO think it should act as both!


$count = 2;
$str = str_replace("ll", "", "good golly miss molly dolly!", $count);
echo $count . ' ' . $str;

Roonaan would be expecting output of ...

2 good goy miss moy dolly!

The actual output is ...

3 good goy miss moy doy!

Trying to run the code with a hard-coded value in the place of $count results in ...

Fatal error: Only variables can be passed by reference in C:\d6.php on line 3

To only replace the first occurance of a substring then use the preg_replace() function as described by kebabs.

Richard QuadlingSenior Software Developer

And just in case Roonaan wants to know what version I'm on ...

<29/03/2006 14:04:30 C:\>php -v
PHP 5.1.3-dev (cli) (built: Feb 20 2006 00:29:25)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies
    with Zend Extension Manager v1.0.10, Copyright (c) 2003-2006, by Zend Technologies
    with Zend Optimizer v3.0.0-Beta2, Copyright (c) 1998-2006, by Zend Technologies
Access more of Experts Exchange with a free account
Thanks for using Experts Exchange.

Create a free account to continue.

Limited access with a free account allows you to:

  • View three pieces of content (articles, solutions, posts, and videos)
  • Ask the experts questions (counted toward content limit)
  • Customize your dashboard and profile

*This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.


Please enter a first name

Please enter a last name

8+ characters (letters, numbers, and a symbol)

By clicking, you agree to the Terms of Use and Privacy Policy.