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Evaluation of logical operations

Filed under: Allgemein — Tags: , , — Thomas @ 21:01

Spass mit dem Standard.
Aus dem Fortran 90/95 Standard [1] Kapitel

Evaluation of logical intrinsic operations
The rules given in 7.2.4 specify the interpretation of logical intrinsic operations. Once the
interpretation of an expression has been established in accordance with those rules, the processor
may evaluate any other expression that is logically equivalent, provided that the integrity of
parentheses in any expression is not violated.
NOTE 7.29
For example, for the variables L1, L2, and L3 of type logical, the processor may choose to
evaluate the expression
L1 .AND. L2 .AND. L3
L1 .AND. (L2 .AND. L3)
Two expressions of type logical are logically equivalent if their values are equal for all possible
values of their primaries.

Aus dem c++11 Standard [2] Kapitel 5.14

The && operator groups left-to-right.

Und die andern Operatoren auch left-to-right.

Aus dem C89 Standard [3] Kapitel 3.3

Except as indicated by the syntax27 or otherwise specified later (for the function-call operator () , && , || , ?: , and comma operators), the order of evaluation of subexpressions and the order in which side effects take place are both unspecified.


[1] http://j3-fortran.org/doc/standing/archive/007/97-007r2/pdf/97-007r2.pdf
[2] http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3337.pdf
[3] https://web.archive.org/web/20050207005628/http://dev.unicals.com/papers/c89-draft.html#3.3

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