Working with variables, data types, and operators in PHP Mocktest

The code first prints the value of $x using the post-decrement operator ($x--), which decrements the value of $x by 1 after returning its current value. So, it prints 5. Then, it prints the updated value of $x, which is 4. Therefore, the output will be 5 4.

The expression "Hello" . " World" uses the concatenation operator (.) to join the strings "Hello" and " World" together. Therefore, the result will be "Hello World", as the two strings are concatenated to form a single string.

The count() function in PHP is used to find the length of an array. It returns the number of elements in the array. Therefore, count($array) will return the length of the array $array.