Character Case in PHP

Задание 1

Given a string:

php<?php
  $str = 'php';
?>

Convert this string into the following string:

php'PHP'

Задание 2

Given a string:

php<?php
  $str = 'PHP';
?>

Convert this string into the following string:

php'php'

Задание 3

Given a string:

php<?php
  $str = 'london';
?>

Convert this string into the following string:

php'London'

Задание 4

Given a string:

php<?php
  $str = 'London';
?>

Convert this string into the following string:

php'london'

Задание 5

Given a string:

php<?php
  $str = 'london is the capital of great britain';
?>

Convert this string into the following string:

php'London Is The Capital Of Great Britain'

Задание 6

Given a string:

php<?php
  $str = 'LONDON';
?>

Convert this string into the following string:

php'London'

Задание 7

Given a string:

php<?php
  $str = 'привет';
?>

Convert this string into the following string:

php'ПРИВЕТ'

Задание 8

Given a string:

php<?php
  $str = 'ПРИВЕТ';
?>

Convert this string into the following string:

php'привет'