Mikroelektronika MIKROE-742 데이터 시트

Function calls are considered to be primary expressions and can be used in situa-
tions where expression is expected. A function call can also be a self-contained
statement and in that case the return value is discarded.

Here’s a simple function which calculates 

xn

based on input parameters 

x

and 

n

(

n

> 0

):

function power(x, n : byte) : longint;
var i : byte;
begin

i := 0; result := 1;
if n > 0 then

for i := 1 to n do result := result*x;

Now we could call it to calculate 312 for example:

tmp := power(3, 12);

Procedure is declared like this:

procedure procedure_name(parameter_list);

{ local declarations }

{ procedure body }

procedure_name

represents a procedure’s name and can be any valid identifier.

Within parentheses, 

parameter_list

is a formal parameter list very similar to vari-

able declaration. In Pascal, parameters are always passed to a procedure by the
value — to pass an argument by address, add the keyword 

var

ahead of identifier.

Local 

declarations

are optional declaration of variables and/or constants, local for

the given procedure. 

Procedure body

is a sequence of statements to be executed

upon calling the procedure.

A procedure is called by its name, with actual arguments placed in the same
sequence as their matching formal parameters. The compiler is able to coerce mis-
matching arguments to the proper type according to implicit conversion rules. Upon
procedure call, all formal parameters are created as local objects initialized by the
values of actual arguments.

Procedure call is a self-contained statement.

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- SOFTWARE AND HARDWARE SOLUTIONS FOR EMBEDDED WORLD

CHAPTER 5