ANSI/IS0 7185-l990 American National Standard for Information Technology - Programming Language PASCAL

88 Pages·1990·4.334 MB·

by  ANSI

INCITS/ISO 7185-1990 (R2003)
(formerly ANSI/IS0 7185-1990
(R1998))
for Information Technology –
Programming Language PASCAL

ANSI/IS0 7185-l 990
Revision and redesignation
of ANSI/IEEE 770.X3.97-1 983 (Ri 990)
American National Standard
for Information Technology -
Programming Language PASCAL
Secretariat
Computer and Business Equipment Manufacturers Association
Approved June 21,1993
American National Standards Institute, Inc.
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Copyright (cid:211) 1990 by Information Technology Industry Council (ITI)
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Contents
Page
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
4 Definitional conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
5 Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
5.1 Processors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
5.2 Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
6 Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
6.1 Lexical tokens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.2 Blocks, scopes, and activations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._................ 8
6.3 Constant definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.4 Types - definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._...................... 11
6.5 Declarations and denotations of variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
6.6 Procedure and function declarations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.7 Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
6.8 Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
6.9 Input and output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ._............ 49
6.10 Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Annexes
A Collected syntax . . . . . . . . . . . . . . . . . . . . . . . .._.._................................................. 58
B Cross - references . . . . . . . . . . . . . . . . . . . . . . . . . . .._.............................................. 64
C Required identifiers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._..................................__.. 71
D Errors . . . . . . . . . . . . . .._.............................................................................. 72
E Implementation - defined features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
F Implementation - dependent features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._.... 78
Foreword
(This foreword is not part of American National Standard ANSI/IS0 7185-
1990. This document is identical to ISO/IEC 7185-l 990, and the following
five paragraphs are the original foreword as it appeared in that document.)
IS0 (the International Organization for Standardization) and IEC (the
International Electrotechnical Commission) form the specialized system for
worldwide standardization. National bodies that are members of IS0 or IEC
participate in the development of International Standards through technical
committees established by the respective organization to deal with particular
fields of technical activity. IS0 and IEC technical committees collaborate in
fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with IS0 and IEC, also take part in the
work.
In the field of information technology, IS0 and IEC have established a joint
technical committee, ISO/IEC JTC 1. Draft International Standards adopted
by the joint technical committee are circulated to national bodies for voting.
Publication as an International Standard requires approval by at least 75%
of the national bodies casting a vote.
International Standard ISO/IEC 7185 was prepared by Joint Technical
Committee ISO/IEC JTC 1, information fechnology.
This second edition cancels and replaces the first edition (IS0 7185:
1983).
Annexes A, B, C, D, E, and F are for information.
This American National Standard reproduces verbatim ISO/IEC 7185:1990
and implements it as an American National Standard that supersedes
ANSI/IEEE 770.X3.97-1983(R1990), which is withdrawn.
Requests for interpretation, suggestions for improvement or addenda, or
defect reports are welcome. They should be sent to the X3 Secretariat,
Computer and Business Equipment Manufacturers Association, 1250 Eye
Street, NW, Suite 200, Washington, DC 20005.
This standard was processed and approved for submittal to ANSI by
Accredited Standards Committee on information Processing Systems, X3.
Committee approval of the standard does not necessarily imply that all
committee members voted for its approval. At the time it approved this
standard, the X3 Committee had the following members:
James D. Converse, Chair
Donald C. Loughry, Vice-Chair
Joanne Flanagan, Secretary
Organization Represented Name of Representative
American Nuclear Society . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Geraldine C. Main
Sally Hartzell (Alt.)
AMP, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._........... Edward Kelly
Charles Brill (Alt.)
AT&T/NCR Corporation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thomas W. Kern
Thomas F. Frost (Alt.)
Apple Computer, Inc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Karen Higginbottom
Association of the Institute
for Certification of Computer
Professionals (AICCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kenneth Zemrowski
Boeing Company..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Catherine Howells
Andrea Vanosdoll (Alt.)
ii
Organization Represented Name of Representative
Bull HN Information Systems, Inc.. ..................................... David M. Taylor
Compaq Computers.. ......................................................... James Barnes
Digital Equipment Corporation ........................................... Delbert Shoemaker
Kevin Lewis (Alt.)
Eastman Kodak Company.. ................................................ James Converse
Michael Nier (Alt.)
Guide International, inc. .................................................... Frank Kirshenbaum
Harold Kuneke (Alt.)
Hewlett-Packard ................................................................ Donald C. Loughry
Hitachi America, Ltd. ......................................................... John Neumann
Kei Yamashita (Ah.)
Hughes Aircraft Company.. ................................................ Harold Zebrack
IBM Corporation ................................................................ Robert H. Follett
Mary Anne Lawler (Alt.)
National Communications Systems .................................... Dennis Bodson
George W. White (Alt.)
National Institute of Standards and Technology.. ................ Robert E. Rountree
Michael Hogan (Alt.)
Northern Telecom, Inc. ...................................................... Mel Woinsky
Subhash Pate1 (Alt.)
Open Systems Foundation (OSF) ...................................... Henry Lowe
Paul Rabin (Alt.)
Recognition Technology Users Association.. ...................... Herbert P. Schantz
G. Edwin Hale (Alt.)
Share, Inc. ........................................................................ Gary Ainsworth
Sony Corporation of America.. ........................................... Michael Deese
Storage Technology Corporation.. ...................................... Joseph S. Zajaczkowski
Samuel D. Cheatham (Alt.)
Sun Microsystems, Inc.. ..................................................... Scott Jameson
Gary S. Robinson (Alt.)
3M Company.. ................................................................... Paul D. Jahnke
Unisys Corporation.. .......................................................... John Hill
Stephen P. Oksala (Alt.)
Use, Inc. ........................................................................... Peter Epstein
U.S. Department of Defense.. ............................................ William Rinehuls
Thomas Bozek (Alt.)
U.S. Department of Energy.. .............................................. Alton Cox
Lawrence A. Wasson (Alt.)
U.S. General Services Administration ................................ Douglas Arai
Larry L. Jackson (Alt.)
U.S. West Corporation.. ..................................................... Gary Dempsey
Anislie Bates (Alt.)
Wang Laboratories, Inc.. .................................................... Steve Brody
Annette Croteau (Alt.)
Wintergreen Information Services.. .................................... John Wheeler
Xerox Corporation ............................................................. Roy Pierce
Paul DeGroat (Alt.)
X3J9, the Technical Advisory Group for the United States, which recom-
mended the adoption of this standard, acknowledges the efforts of all
those who contributed to the original standards, BS 6192:1982 (IS0
7185:1983) and ANSI/IEEE 770.X3.97-1983(R1990), on which this revi-
sion is based. It also acknowledges the efforts of all those who actively
participated in the revision of IS0 7185, in particular:
David Bustard Tony Hetherington Steve Siegfried
Barry Byrne Steve Hobbs John Souter
Klaus Daessler David Joslin Manfred Stadel
Norman Diamo nd Katsuhiko Kakehi Bob Tennent
Bob Dietrich Jim Miner Tom Turba
Ken Edwards Wes Munsil Eiiti Wada
Jacques Farre Bill Price Willem Wakker
Harris Hall John Reagan Brian Wichmann
Carsten Hammer Arthur Sale
Atholl Hay Paula Schwartz
Introduction
This International Standard provides an unambiguous and machine independent definition of the
programming language Pascal. Its purpose is to facilitate portability of Pascal programs for use on a
wide variety of data processing systems.
Language history
The computer programming language Pascal was designed by Professor Niklaus Wirth to satisfy two
principal aims
a) to make available a language suitable for teaching programming as a systematic discipline based on
certain fundamental concepts clearly and naturally refiected by the language;
b) to define a language whose implementations could be both reliable and efficient on then-available
computers.
However, it has become apparent that Pascal has attributes that go far beyond these original goals. It is
now being increasingly used commercially in the writing of both system and application software. This
International Standard is primarily a consequence of the growing commercial interest in Pascal and the
need to promote the portability of Pascal programs between data processing systems.
In drafting this International Standard the continued stability of Pascal has been a prime objective.
However, apart from changes to clarify the specification, two major changes have been introduced.
a) The syntax used to specify procedural and functional parameters has been changed to require the
use of a procedure or function heading, as appropriate (see 6.6.3.1); this change was introduced to
overcome a language insecurity.
b) A fifth kind of parameter, the conformant-array-parameter, has been introduced (see 6.6.3.7). With
this kind of parameter, the required bounds of the index-type of an actual-parameter are not fixed,
but are restricted to a specified range of values.
Project history
In 1977, a working group was formed within the British Standards Institution (BSI) to produce a standard
for the programming language Pascal. This group produced several working drafts, the tirst draft for public
comment being widely published early in 1979. In 1978, BSI’s proposal that Pascal be added to ISO’s
program of work was accepted, and the IS0 Pascal Working Group (then designated ISO/TC97/SCYWG4)
was formed in 1979. The Pascal standard was to be published by BSI on behalf of ISO, and this British
Standard referenced by the International Standard.
In the USA, in the fall of 1978, application was made to the IEEE Standards Board by the IEEE Computer
Society to authorize project 770 (Pascal). After approval, the first meeting was held in January 1979.
In December of 1978, X3J9 convened as a result of a SPARC (Standards Planning and Requirements
Committee) resolution to form a US TAG (Technical Advisory Group) for the IS0 Pascal standardization
effort initiated by the UK. These efforts were performed under X3 project 317.
In agreement with IEEE representatives, in February of 1979, an X3 resolution combined the X3J9 and
P770 committees into a single committee called the Joint X3J9/lEEE-P770 Pascal Standards Committee.
(Throughout, the term JPC refers to this committee.) The tirst meeting as JPC was held in April 1979.
The resolution to form JPC clarified the dual function of the single joint committee to produce a dpANS
and a proposed IEEE Pascal standard, identical in content.
ANSI/IEEE77OX3.97-1983, American National Standard Pascal Computer Programming Language, was
approved by the IEEE Standards Board on September 17,1981, and by the American National Standards
iv
Institute on December 16, 1982. British Standard BS6192, Specification for Computer programming
language Pascal, was published in 1982, and International Standard 7185 (incorporating BS6192 by
reference) was approved by IS0 on December 1,1983. Differences between the ANSI and IS0 standards
are detailed in the Foreword of ANSI/IEEE770X3.97-1983.
In 1985, the IS0 Pascal Working Group (then designated ISO/TC97/SC22/WG2, now ISO/IEC JTCl/
SC22/WG2) was reconvened after a long break. An Interpretations Subgroup was formed, to interpret
doubtful or ambiguous portions of the Pascal standards. As a result of the work of this subgroup, and also
of the work on the Extended Pascal standard being produced by WG2 and JPC, BS6192/IS07185 was
revised and corrected during 1988/89; it is expected that ANSI/IEEE77OX3.97-1983 will be replaced by
the revised IS0 7 185.
The major revisions to BS6192: 1982 to produce the new IS0 7 185 are:
a) resolution of the differences with ANSI/IEEE77OX3.97-1983;
b) relaxation of the syntax of real numbers, to allow “digit sequences” rather than “unsigned integers”
for the various components;
c) in the handling of “end-of-line characters” in text files;
d) in the handling of run-time errors.