How to use the PHP function for character replacement?

There are many character replacement functions available in PHP, with commonly used functions being str_replace() and preg_replace().

1. Replace characters using the str_replace() function.

$string = "Hello, world!";
$new_string = str_replace("Hello", "Hi", $string);
echo $new_string; // Output: Hi, world!

1. Perform regular expression replacement using the preg_replace() function.

$string = "Hello, world!";
$new_string = preg_replace("/\bworld\b/", "universe", $string);
echo $new_string; // Output: Hello, universe!

These are two common methods of character replacement, choose the one that best fits your needs for character replacement.