Re: THe type of Indexes in Open Array Parameters

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Article #544

#544

From: Charles D. Farnum
Date: Fri, 03 Oct 1986 18:13

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In article <12243873849.8.PATTIS@WARD.CS.WASHINGTON.EDU> PATTIS@WARD.CS.WASHINGTON.EDU (Richard Pattis) writes:
>What is the type of the index in open array parameters?  How can you justify
>your answer (quotes from Wirth)? ...

According to the third edition of ``Programming in Modula-2'', p. 152,
section 8.1 of the Report:

    ...the designator A[E] denotes that component of A whose index is the 
    current value of the expression E.  The index type of A must be
    _assignment_compatible_ [emphasis Wirth's] with the type of E...

The index type of an open array thus becomes academic; if we assume that
it is some subrange of CARDINAL or INTEGER, then it doesn't matter which
choice we make since subranges of CARDINAL and INTEGER are assignment
compatible (section 9.1).

  /charlie

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Path: arc1-ca.pugleaf.net!utzoo!watmath!clyde!cbatt!cbosgd!ucbvax!renoir.Berkeley.EDU!farnum
From: farnum@renoir.Berkeley.EDU (Charles D. Farnum)
Newsgroups: net.lang.mod2
Subject: Re: THe type of Indexes in Open Array Parameters
Message-ID: <15903@ucbvax.BERKELEY.EDU>
Date: Fri, 3-Oct-86 14:13:07 EDT
Article-I.D.: ucbvax.15903
Posted: Fri Oct  3 14:13:07 1986
Date-Received: Sat, 4-Oct-86 12:28:57 EDT
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