What is the best PHP function to use for replacing specific characters in a string?

When you need to replace specific characters in a string in PHP, the `str_replace()` function is commonly used. This function allows you to specify the characters you want to replace and what you want to replace them with. By using `str_replace()`, you can easily manipulate strings and modify them as needed.

// Replace specific characters in a string using str_replace()
$string = "Hello, World!";
$new_string = str_replace(",", "!", $string);
echo $new_string; // Output: Hello! World!