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Functions and Procedures

Introduction to Functions and Procedures

Functions

Functions are algorithms that can be called to execute an already written set of code, and return a value to where they were called. They use the keywords FUNCTION, RETURNS, ENDFUNCTION. Functions can be used either with or without parameters.

FUNCTION <function name> RETURNS <data type to return>
    <code to be executed>
ENDFUNCTION

Alternatively, with parameters:

FUNCTION <function name>(<parameter1> : <data type>,
                         <parameter2> : <data type>...)
                         RETURNS <data type to return>
    <code to be executed>
ENDFUNCTION

The keyword RETURN is used to specify a value to be returned within the function. Upon encountering a RETURN statement, it is executed immediately, and any lines after the statement are ignored.

FUNCTION Add(num1 : INTEGER, num2 : INTEGER) RETURNS INTEGER
    num3 <- num1 + num2
    RETURN num3
ENDFUNCTION

Procedures

Procedures are similar to functions, however they do not return any value. They use the keywords PROCEDURE, ENDPROCEDURE. Procedures can also be used with or without parameters.

PROCEDURE <procedure name>
    <code to be executed>
ENDPROCEDURE

With parameters:

PROCEDURE <procedure name>(<parameter1> : <data type>, 
                           <parameter2> : <data type>...)
    <code to be executed>
ENDPROCEDURE

Procedures must be called using the CALL keyword, used respectively as follows:

CALL <procedure name>

CALL <procedure name>(<parameter1>, <parameter2>, ...)

An example of procedure definition and calling:

PROCEDURE Add(num1 : INTEGER, num2 : INTEGER)
    num3 <- num1 + num2
    OUTPUT num3
ENDPROCEDURE

CALL Add(10, 5)