Software DD (Implementation: Parameter Passing)

Question 1

Formal Parameters

Answer 1

Formal parameters are the identifiers used to stand for a value that will be passed when a subprogram/method is called:
def CelsiusToFahr(celsius):

From RGC Aberdeen website

Question 2

Actual Parameters

Answer 2

Actual parameters are the actual values that is passed into the method/subroutine/function.
Fahrenheit = CelsiusToFahr(78)
or
Fahrenheit = CelsiusToFahr(inputtemp)

From RGC Aberdeen website

Question 3

Global Variable

Answer 3

A global variable means it is accessible in EVERY sub-routine of the entire program.
* Python assumes each variable is local if is specified inside a subroutine.
* Python assumes each variable is global if it is specified outside of a subroutine.
This is not a good idea….
* This means EVERY subroutine can change them accidentally.
* The way to counter this is to use local variables.

From RGC Aberdeen website

Question 4

Local Variable

Answer 4

Local variables only exist in the subroutine in which they are declared. This is known as the scope of a variable.

For example if there was a variable called counter that was used to control loops and your program had numerous loops then that variables value would change all the time.

From RGC Aberdeen website

Question 5

Advantages of Local Variables

Answer 5

• Aids modularity
  Allows subroutines to be used with their own variables
• More efficient in terms of memory
  Local variables are disposed of when the subroutine finishes
• Removes naming clashes with other local variables in other subroutines
  E.g loop counter variables

From RGC Aberdeen website

Question 6

Functions and Subroutines

Answer 6

A function returns a value(s) which can be assigned to a variable. Where as a subroutine may not pass out any values.

From RGC Aberdeen website