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Operators

Operators must be defined on values of specific types. For instance, + is defined on numbers, but not on structures. Operators are often defined on groups of types. For the purposes of Modula-2, the following definitions hold:

The following operators are supported, and appear in order of increasing precedence:

,
Function argument or array index separator.
:=
Assignment. The value of var := value is value.
<, >
Less than, greater than on integral, floating-point, or enumerated types.
<=, >=
Less than or equal to, greater than or equal to on integral, floating-point and enumerated types, or set inclusion on set types. Same precedence as <.
=, <>, #
Equality and two ways of expressing inequality, valid on scalar types. Same precedence as <. In scripts, only <> is available for inequality, since # conflicts with the script comment character.
IN
Set membership. Defined on set types and the types of their members. Same precedence as <.
OR
Boolean disjunction. Defined on boolean types.
AND, &
Boolean conjunction. Defined on boolean types.
@
The "artificial array" operator (see section Expressions).
+, -
Addition and subtraction on integral and floating-point types, or union and difference on set types.
*
Multiplication on integral and floating-point types, or set intersection on set types.
/
Division on floating-point types, or symmetric set difference on set types. Same precedence as *.
DIV, MOD
Integer division and remainder. Defined on integral types. Same precedence as *.
-
Negative. Defined on INTEGER and REAL data.
^
Pointer dereferencing. Defined on pointer types.
NOT
Boolean negation. Defined on boolean types. Same precedence as ^.
.
RECORD field selector. Defined on RECORD data. Same precedence as ^.
[]
Array indexing. Defined on ARRAY data. Same precedence as ^.
()
Procedure argument list. Defined on PROCEDURE objects. Same precedence as ^.
::, .
and Modula-2 scope operators.

Warning: Sets and their operations are not yet supported, so treats the use of the operator IN, or the use of operators +, -, *, /, =, , <>, #, <=, and >= on sets as an error.


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