5.13     Exercises

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1. What is the difference between an associative array and a multidimensional array?

2. How many times should srand() be called?

   • a) Once ever

   • b) Once per script

   • c) Once for every call to shuffle(), before the call

   • d) Once for every call to shuffle(), after the call

3. To safely pass an array over the web, what is the correct sequence of function calls:

   • a) urlencode(), serialize(), unserialize(), urldecode()

   • b) urldecode(), unserialize(), serialize(), urlencode()

   • c) serialize(), unserialize(), urlencode(), urldecode()

   • d) serialize(), urlencode(), urldecode(), unserialize()

4. When passing a negative "step" parameter to the range() function, the initial value must always be larger than the end value: true or false?

5. To randomise the order of an array, which function(s) can you use:

   • a) shuffle()

   • b) mt_shuffle()

   • c) Both of the above

   • d) Neither a) nor b)

6. Which of the following statements are true about arrays that have a hole (e.g. it has keys 0, 1, 2, and 4):

   • a) You can use foreach to loop through the array and ignore the hole

   • b) You can use the array_values() function to re-order the keys

   • c) You can use the arsort() function to re-order the keys

   • d) All of the above