Q What PHP function is used to sort a multidimensional array by value? To sort the multidimensional array while maintaining the keys? To sort the multidimensional array by key? (See page 3.)

A: usort, uasort, uksort:

Q When writing a function to be used to sort a multidimensional array, what values should it return? (See page 3.)

A: a comparative of two array values

Q What is a recursive function? In what situations are they useful? What are the two things to be careful of when using them? (See page 17.)

A: Function that calls itself. Useful in arrays of unknown depth/dimension. With more than 100 iterations, they can max out the server.

Q What is a static variable? In what situations are static variables helpful? (See page 24.)

A: Variable that keeps its state between function calls. Only nested calls?

Q What is an anonymous function? When were anonymous functions added to PHP? (See page 27.)

A: Function with no name. started in 5.3

Q What are the rules for using the heredoc syntax? What advantages does heredoc have over alternative approaches? (See page 31.)

Start must have TAG, then >>> and no space after

end must have TAG and no space before

Q How do you use the printf() and sprintf() functions? What benefits do they offer? (See page 37.)

Formatting statements and variables for different output types. I've used in queries thanks to Dreamweaver's default functions.