What are some common methods for finding and replacing specific text parts within a PHP string?

When working with PHP strings, it is common to need to find and replace specific text parts within the string. One common method is to use the `str_replace()` function, which allows you to search for a specific substring and replace it with another substring. Another method is to use regular expressions with functions like `preg_replace()`, which provides more advanced pattern matching capabilities. Both methods are useful for manipulating strings in PHP.

// Using str_replace() to find and replace specific text parts within a PHP string
$string = "Hello, World!";
$new_string = str_replace("Hello", "Hi", $string);
echo $new_string;

// Using preg_replace() with regular expressions to find and replace specific text parts within a PHP string
$string = "The quick brown fox jumps over the lazy dog";
$new_string = preg_replace("/brown fox/", "red fox", $string);
echo $new_string;