Variable roles

Question 1

What does a fixed value variable do?

Answer 1

The value of the variable is not changed whilst the program is running after initialisation

Question 2

What does a stepper variable do?

Answer 2

Goes through a series of values in a systematic way

eg. a counter for a loop, going through an array, counting

Question 3

What does a most-recent holder variable do?

Answer 3

Changes to hold the latest current value and is regularly updated

Question 4

What does a most-wanted holder variable do?

Answer 4

The ‘best’ value out of the values gone through at that point. What is most wanted depends on the program, eg. smallest, largest, closest to a certain number etc

Question 5

What does a gatherer variable do?

Answer 5

Accumulates all values gone through so far

Question 6

What does a follower variable do?

Answer 6

Always takes the old value of another variable as its own value

Question 7

What does a transformation variable do?

Answer 7

Always gets its value from a fixed calculation using other variable’s values
eg. variable 1 = contents of variable 2 x 5, the 5 doesn’t change

Question 8

What does a temporary variable do?

Answer 8

Its value is only needed for a very short time

Question 9

What is a value parameter?

Answer 9

A parameter in a subroutine which enables a one way only flow of data from main program into routine.
The routine cannot change the global value of the variable
=routine variable in brackets without var in front of it

Question 10

What is a reference parameter?

Answer 10

A parameter in a subroutine which enables a two way flow data between main program and routine, routine can change the global value of a variable
=routine variable with VAR in front of it in the brackets

Question 11

What is the difference between a procedure and a function?

Answer 11

Both are subroutines but a function always returns a value, procedures just executes commands

Question 12

What is a global variable?

Answer 12

Declared at the start of the program and can be used in any subroutine without being declared or passed again
They use memory even when not being used

Question 13

Why is it better to use local variables than global variables, where possible?

Answer 13

• Makes program more easy to read and understand
• Makes subroutines easier to re-use
• Global variables can have unexpected side effects
• Global variables use memory even when subroutine is not being executed.

Question 14

What is a local variable?

Answer 14

Declares at the start of a subroutine, can only be used in the subroutine they were declared in unless passed to a different part of the program
They only use memory when their subroutine is being executed