How to Replace a Substring in a String using Regular Expression in PHP - Step by Step Examples

How to Replace a Substring in a String using Regular Expression in PHP ?

To replace all occurrences of a substring in a string using regular expression in PHP, you can use the preg_replace function.

In this example,

We create a string named $str.
We use the preg_replace function on $str with a regex pattern matching "Hello" and replace it with "Hi".
The preg_replace function returns a new string with all occurrences replaced.
Finally, we print the modified string.

<?php 
$str = "Hello World Hello";
$newStr = preg_replace('/Hello/', 'Hi', $str);
echo $newStr;
?>

Hi World Hi

In this example,

We create a string named $str.
We use the preg_replace function on $str with a regex pattern matching digits (\d) and replace them with 'Y'.
The preg_replace function returns a new string with all occurrences replaced.
Finally, we print the modified string.

<?php 
$str = "Hello123World789";
$newStr = preg_replace('/\d/', 'Y', $str);
echo $newStr;
?>

HelloYYYWorldYYY

In this tutorial, we learned How to Replace a Substring in a String using Regular Expression in PHP language with well detailed examples.