Basic Characteristics RAPID

Expressions Basic Characteristics RAPID
simply considered to be omitted. Note that the specified parameter must be optional.
Example: PROC Read_from_file (iodev File \num Maxtime)
..
character:=ReadBin (File \Time?Maxtime);
! Max. time is only used if specified when calling the routine
! Read_from_file
..
ENDPROC
The parameter list of a function assigns an access mode to each parameter. The access
mode can be either in, inout, var or pers:
- An IN parameter (default) allows the argument to be any expression. The called
function views the parameter as a constant.
- An INOUT parameter requires the corresponding argument to be a variable
(entire, array element or record component) or an entire persistent. The called
function gains full (read/write) access to the argument.
- A VAR parameter requires the corresponding argument to be a variable (entire,
array element or record component). The called function gains full (read/write)
access to the argument.
- A PERS parameter requires the corresponding argument to be an entire persistent.
The called function gains full (read/update) access to the argument.
7.7 Priority between operators
The relative priority of the operators determines the order in which they are evaluated.
Parentheses provide a means to override operator priority. The rules below imply the
following operator priority:
* / DIV MOD - highest
+ -
< > = =
AND
XOR OR NOT - lowest
An operator with high priority is evaluated prior to an operator with low priority. Operators
of the same priority are evaluated from left to right.
Example
Expression Evaluation order Comment
a + b + c (a + b) + c left to right rule
a + b * c a + (b * c) * higher than +
a OR b OR c (a OR b) OR c Left to right rule
5-30 RAPID Reference Manual