Next: , Up: Modula-2   [Contents][Index] 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 GDB scripts, only <> is available for inequality, since # conflicts with the script comment character.


Set membership. Defined on set types and the types of their members. Same precedence as <.


Boolean disjunction. Defined on boolean types.

AND, &

Boolean conjunction. Defined on boolean types.


The GDB “artificial array” operator (see 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 *.


Integer division and remainder. Defined on integral types. Same precedence as *.


Negative. Defined on INTEGER and REAL data.


Pointer dereferencing. Defined on pointer types.


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 ^.

::, .

GDB and Modula-2 scope operators.

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

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