Fundamentals of Programming

Question 1

Algorithm

Answer 1

a sequence of steps to complete a task

Question 2

Definite iteration

Answer 2

For loop

the number of iterations is known (at the time of execution);

Question 3

Indefinite iteration, condition at the start

Answer 3

While loop

Indefinite iteration: the number of iterations depends on a condition (that is tested before / after each iteration);

Question 4

Indefinite iteration, condition at the end

Answer 4

Repeat until

Indefinite iteration: the number of iterations depends on a condition (that is tested before / after each iteration);

Question 5

Global variable

Answer 5

Global variable can be used anywhere in program // global variable is declared in outmost block / outside subroutines;

global variables use memory the entire time the program is executing;

global variables exist the entire time the program is running;

Question 6

Local variable

Answer 6

Local variable can only be used in the block / subroutine in which it is declared;

Local variables only use memory when the program block they are in is executing;

Local variables only exist when the program block they are in is executing;

Question 7

State one difference between local and global variables and give two reasons why it is good practice to use local variables.

Answer 7

Difference:

global variables accessible to all parts of the program

// declared in main program block

// local variables declared in subroutine

// accessible only in the program block/subroutine in which it was declared;

Reason:

memory allocated to local variables can be reused when subroutine not in use;

local variable only exists while the program block/subroutine is executing;

using local variables makes subroutines self-contained;

A. prevents accidental changes;

A. easier debugging/maintenance;

Question 8

Why is it good practice to use local variables?

Answer 8

1.   makes a subroutine self-contained;

2.   releases storage when subroutine terminates;

3.   able to test / debug subroutine independently;

4.   easier to re-use subroutine in another program;

5.   local variable values cannot be inadvertently/accidentally altered by a subroutine call from the subroutine;

Question 9

Explain one difference between a procedure and a function.

Answer 9

Functions always return some value when called;

Procedures may return a value;

Functions appear in expressions;

Procedures do not appear in expressions;

Procedures name alone makes up the statement / call <name></name>