User manual
mikroPascal PRO for dsPIC30/33 and PIC24
MikroElektronika
199
Note: Label should be followed by end of line (CR) otherwise compiler will report an error.
label loop;
...
loop: Beep; // compiler will report an error
loop: // compiler will report an error
Functions and Procedures
Functions and procedures, collectively referred to as routines, are subprograms (self-contained statement blocks) which perform
a certain task based on a number of input parameters. When executed, a function returns a value while procedure does not.
Functions
A function is declared like this:
function function_name(parameter_list) : return_type;
{ local declarations }
begin
{ function body }
end;
function_name represents a function’s name and can be any valid identier. return_type is a type of return
value and can be any simple type or complex type. Within parentheses, parameter_list is a formal parameter list
very similar to variable declaration. In Pascal, parameters are always passed to a function by the value. To pass an
argument by address, add the keyword var ahead of identier.
Local declarations are optional declarations of variables and/or constants, local for the given function. Function
body is a sequence of statements to be executed upon calling the function.
Calling a function
A function is called by its name, with actual arguments placed in the same sequence as their matching formal parameters.
The compiler is able to coerce mismatching arguments to the proper type according to implicit conversion rules. Upon
a function call, all formal parameters are created as local objects initialized by values of actual arguments. Upon return
from a function, a temporary object is created in the place of the call and it is initialized by the value of the function
result. This means that function call as an operand in complex expression is treated as the function result.
In standard Pascal, a function_name is automatically created local variable that can be used for returning a value of
a function. mikroPascal PRO for dsPIC30/33 and PIC24 also allows you to use the automatically created local variable
result to assign the return value of a function if you nd function name to be too ponderous. If the return value of a
function is not dened the compiler will report an error.
Function calls are considered to be primary expressions and can be used in situations where expression is expected.
A function call can also be a self-contained statement and in that case the return value is discarded.