Get your next remote job on LaraJobs.
1 contributor Edit on GitHub PHP

PHP's str_replace() made simple

Table of contents:

PHP's str_replace() made simple

Introduction

PHP provides a plethora of built-in functions, with str_replace() being one of the my favorite.

This function is fundamental to handling and manipulating strings, playing an essential role in many PHP applications.

The basics of the str_replace() function in PHP

The str_replace() function in PHP replaces strings with other strings. It’s that simple, yet powerful.

Its signature looks like this:

str_replace(
string|array $search,
string|array $replace,
string|array $subject,
int &$count = null
) : string|array
  • search: It specifies the value to find. It can either be a string or an array.
  • replace: It defines the value to replace the found value with. It can either be a string or an array.
  • subject: It’s the string or array to be searched and replaced on. It can either be a string or an array.
  • count: It’s an optional integer and determines the number of replacements performed.

To me, examples speak more than theory. Let’s explore how to use str_replace().

Practical use cases of str_replace() in PHP

Classic search and replace

Let’s say we have a greeting “Hello, unknown person!” and we want to change “unknown person” to “Benjamin”.

Using str_replace(), we can achieve this like so:

$sentence = 'Hello, unknown person!';
 
echo str_replace('unknown person', 'Benjamin', $sentence);
 
// Outputs: Hello, Benjamin!

Search and replace multiple values

str_replace() can also be used with arrays, sequencially searching and replacing the values.

This can avoid you to call str_replace() multiple times.

For example:

$sentence = '1st, 2nd, and 3rd.';
 
echo str_replace(
['1st', '2nd', '3rd'],
['first', 'second', 'third'],
$sentence
);
 
// Outputs: first, second, and third.

Search and replace in an array of strings

str_replace() accepts a value of type array as the subject.

Which means you can still avoid calling str_replace multiple times if you are able to build an array of subjects. I didn’t know that before writing this article!

Let me show you:

$sentences = [
'You cannot mention Mastodon on Twitter!',
"Let's build a new society on Mastodon!",
'Is Mastodon a Twitter-killer?',
];
 
var_dump(
str_replace(
'Mastodon',
'@&$!?%',
$sentences
)
);
 
// Outputs: [
// 'You cannot mention @&$!?% on Twitter!',
// "Let's build a new society on @&$!?%!",
// 'Is @&$!?% a Twitter-killer?',
// ]

PHP’s str_ireplace() isn’t case sensitive

The str_replace() function is case-sensitive.

If you need case-insensitive replacement, PHP offers the str_ireplace() function.

echo str_ireplace('foo', 'bar', 'FOo foo fOO');
 
// Outputs: bar bar baz

The limitations of the str_replace() function in PHP

While versatile, str_replace() has its limitations:

  • No direct support for regular expressions: As mentioned, str_replace() does not support regex. For this, you’ll need to use preg_replace().
  • It’s unable to replace multi-byte unicode characters: The str_replace() function is not safe for multi-byte characters like those found in UTF-8 strings.
  • There are problems with case sensitivity: As noted before, str_replace() is case-sensitive. If you need to ignore case, use str_ireplace().
Benjamin Crozat

Written by Benjamin Crozat

Indie hacker, blogger, and AI enthusiast building things with the TALL stack. 🔥

Follow me on:

Recommended articles

The fastest way to check if your PHP array is empty The fastest way to check if your PHP array is empty

There are multiple ways to check if an array is empty. Let me tell you about each of them and why and when you should use them.

Modified on Nov 2, 2023 Audio available

PHP
PHP 8.3 is out, now! Here's what's new and changed. PHP 8.3 is out, now! Here's what's new and changed.

PHP 8.3 was released on November 23, 2023, and as usual, you need to be up to date with new features and breaking changes for easier transitions.

Modified on Nov 23, 2023

PHP
Print an array with PHP (+ Laravel) Print an array with PHP (+ Laravel)

Debugging requires dissecting everything. Here's a list of all the one-line of code built-in ways to print arrays in PHP (and even Laravel-specific helpers).

Modified on Jun 24, 2023

console.log() in PHP console.log() in PHP

Explore the world of PHP debugging with var_dump(), and Laravel's friendlier alternatives, dump() and dd(). Much charm, such useful!

Modified on Sep 6, 2023

PHP

Gold sponsors New

  • Wire Elements
    Beautiful handcrafted Livewire components.
    Check site
Your business here

Partners

If you buy from one of my partners below, I will be compensated at no cost to you. These are services I use or used, and 100% stand behind.

  • Scalable and reliable VPS hosting.
    Bonus: $200 of free credits
    Check site
  • The Google Analytics alternative without compromise.
    Free trial: 30 days
    Bonus: $10 off your first invoice
    Check site
  • Flare
    Track PHP and JavaScript errors in one place.
    Free trial: 10 days
    Check site
  • Keep track of your Google rankings.
    Free trial: 7 days
    Promo code: WELCOME30
    Check site
- / -