Re: Report on defect in M2 vs C (Was Modula-2, Modula-3, C or C++)

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Article #2622

#2622

From: Robert Dewar
Date: Sat, 14 Oct 1995 19:36

8 lines
1175 bytes

        char p[10], q[10];
        int r = &p[5] - &q[2];

this is plainly incorrect C, so this is not the kind of issue that arises
in bounds checking. THe problem is that pointers can be havily aliased 
in C, and I repeat my observation, without auxiliary data structures of som
e kind you can't tell if a pointer is a pointer to an integer or a pointer
to an element of an array, so you can't tell if it is valid to decrement it.

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Path: arc1-ca.pugleaf.net!news.mathworks.com!panix!cmcl2!schonberg!dewar
From: dewar@cs.nyu.edu (Robert Dewar)
Newsgroups: comp.lang.modula2,comp.lang.modula3,comp.lang.c,comp.lang.c++,comp.lang.ada
Subject: Re: Report on defect in M2 vs C (Was Modula-2, Modula-3, C or C++)
Date: 14 Oct 1995 15:36:38 -0400
Organization: Courant Institute of Mathematical Sciences
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