Campbell Scientific CR9000X Measurement and Control System - Manual (Page 162)

Section 4. CRBasic – Native Language Programming
4.2.11 Expressions
An expression is a series of words, operators, or numbers that produce a value
or result. Expressions are evaluated from left to right, with deference to
precedence rules. Table 4.2.11-1 lists the order of precedence for the operators
supported by the CR9000X. The result of each stage of the evaluation is of
type Long (integer) if the variables are of type Long (constants are integers) and
the functions give integer results, such as occurs with INTDV (). If part of the
equation has a floating point variable or constant, or a function that results in a
floating point, the rest of the expression will be evaluated using floating point
math, even if the final function is to convert the result to an integer; e.g. INT
((rtYear-1993)*.25). This is a critical feature to consider when:
1) trying to use Long integer math to retain numerical resolution beyond the
limit of floating point variables (24 bits), or
2) if the result is to be tested for equivalence against another value.
Table 4.2.11-1 Precedence ranking of operators
Rank Symbols Functions
1 ^ Raise to power
2 +, -
NOT Positive, Negative
Logical Negation
3 *, /
INTDV, MOD
Multiply, Divide
Integer division, Modulo divide
4 +, -,
+, & Addition, Subtraction,
String concatenation
5 =, <>
<, <=
>, >=
IS Equal, Not equal
Less than, Less than or equal
Greater than, Greater than or equal
Select Case
6 <<, >>
AND, OR
XOR, IMP
EQV Bit shift right, Bit shift left
Logical conjunction, Logical disjunction
Logical exclusion, Logical implication
Bit wise comparision
Two types of expressions, mathematical and logical, are used in CRBASIC. A
useful property of expressions in CRBASIC is that they are equivalent to and
often interchangeable with their results.
Consider the expressions:
x = (z * 1.8) + 32 (a mathematical expression)
If x = 23 then y = 5 (logical expression)
The variable x can be omitted and the expressions combined and written as:
If (z * 1.8 + 32 = 23) then y = 5
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