2.2.1 Programming Techniques

Question 1

what is the difference between global and local variables

Answer 1

Global variables can be accessed from the entire program
Local variables have a limited scope where they can only be accessed from the module of code they were defined in

Question 2

what is the difference of passing in a parameter byval and byref

Answer 2

by value means that a coy of the data is given to the subroutine meaning anychanges to the data made inside the subroutine dont change the value passed in
by ref gives the address of the data to the subroutine meaning any changes to the data update the address as its changed

Question 3

what are the two ways to pass parameters into a subroutine

Answer 3

by reference and by value

Question 4

define a recursive algorithm

Answer 4

a recursive algorithm is a function which calls itself from within the function

Question 5

name the pros of a recursive algorithm

Answer 5

Certain problems are more suited to a recursive solution
problems can be more elegantly solved
can reduce the size of the problem on every recursive call
more natural to read
quicker to write

Question 6

name the cons of recursion

Answer 6

uses more memory
can run out of stack space
difficult to debug
harder to trace

Question 7

example of a time recursion is idea

Answer 7

factorial
fibbonnacci
tree traversal