Rice Lake iRite IDE - Manual (Page 17)

920i Programming Reference - Language Syntax 13 To be the best by every measure
When using the divide operator with integers, be careful of losing significant digits. For example, if you are
dividing a smaller integer by a larger integer then the result is an integer zero: 4/7 = 0. If you were hoping to
assign the result to a real like in the following example:
rSlope : real;
rSlope := 4/7;
rSlope will still equal 0, not 0.571428671 as might be expected. This is because the compiler does integer math
when both operands are integers, and stores the result in a temporary integer. To make the previous statement
work in
iRite , one of the operands must be a real data type or one of the operands must evaluate to a real. So we
could write the assignment statement like:
rSlope := 4.0/7;
If we were dividing two integer variables, we could multiply one of the operands by 1.0 to force the compile to
resolve the expression to a real:
rSlope : real;
iRise : integer := 4;
iRun : integer := 7;
rSlope := (iRise * 1.0) / iRun;
Now rSlope will equal 0.571428671.
Note
The plus sign (+) is also used as the string concatenation operator. The minus sign (–) is also used as a
unary minus operator that has the result equal to the negative of its operand.
Assignment Operator (:=)
The assignment operator is used to assign a value to a compatible program variable or to initialize a constant. The
value on the left of the “:=” must be a modifiable value. The following are some invalid examples:
3 := 1 + 1; -- not valid
ciMaxAge := 67; -- where ciMaxAge was declared with keyword constant
iInteger := "This is a string, not an integer!"; -- incompatible types
Structure Member Operator (“dot”)
The “dot” (.) is used to access the name of a field of a record or database types.
3.2 Program Structure
A program is delimited by a program header and a matching end statement. The body of a program contains a
declarations section, which may be empty, and an optional main code body. The declaration section and the main
code body may not both be empty.
:
program IDENTIFIER ’;’
end IDENTIFIER ’;’
;
:
/* NULL */
| begin
;
PROGRAM IDENTIFIER
;
END IDENTIFIER
;
decl-section optional-main-body
Figure 3-1. Program Statement Syntax