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Procedures and Functions

Programming · 4 question types

Practise

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 4% of your exam marks.

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Rare
Stable4%

Writing and calling procedures/functions with parameters is tested in Paper 2.

A procedure is a named block of code that performs a task without returning a value. It is invoked using the CALL keyword.

Defining a procedure

A procedure with no parameters:

PROCEDURE ProcedureName
   // statements that do the work
ENDPROCEDURE

A procedure with (values passed in):

PROCEDURE ProcedureName(Param1 : TYPE, Param2 : TYPE, ...)
   // statements that use the parameters
ENDPROCEDURE

Each parameter is named and given a data type, so the procedure knows what kind of value to expect.

Calling a procedure

Procedures are run using the CALL keyword:

CALL ProcedureName
CALL ProcedureName(Value1, Value2)

The values in brackets are called . Each argument is matched in order to the corresponding parameter in the procedure's definition.

When to use a procedure

Choose a procedure when the sub-program's job is to do something rather than to compute and return something:

  • Show a menu on screen.
  • Save data to a file.
  • Display a report.
  • Reset all the variables to a known starting state.