What is the purpose of using ucfirst() and substr() functions in PHP, and how can they be used effectively together?

The ucfirst() function in PHP is used to capitalize the first letter of a string, while the substr() function is used to extract a substring from a string. By using ucfirst() in combination with substr(), you can capitalize the first letter of a specific substring within a string. Example:

$string = "hello world";
$substring = substr($string, 6); // Extract "world"
$capitalizedSubstring = ucfirst($substring); // Capitalize the first letter of the substring
$result = substr_replace($string, $capitalizedSubstring, 6); // Replace the original substring with the capitalized one

echo $result; // Output: "hello World"