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From: tanmoy@qcd.lanl.gov (Tanmoy Bhattacharya)
Subject: Re: What's the best language to start with? [was: Re: Should I learn
 C or Pascal?]
Date: 1996/08/27
Message-ID: <TANMOY.96Aug27132311@qcd.lanl.gov>#1/1
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references: <31FBC584.4188@ivic.qc.ca>
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organization: Los Alamos National Laboratory
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newsgroups: comp.lang.c,comp.lang.c++,comp.unix.programmer,comp.lang.ada
Date: 1996-08-27T00:00:00+00:00
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In article <slrn523tpg.ce.mdw@excessus.demon.co.uk>
mdw@excessus.demon.co.uk (Mark Wooding) writes:
<snip>
MW: locally allocated buffers.  If the buffer is not local to the function,
MW: there's no guarantee that (in an extreme case) its address hasn't been
MW: made available to a signal handler which maliciously changes the
MW: string's length.

In C, a signal handler is not allowed to change anything whose type
isn't volatile sigatomic_t. So, technically, a C compiler can ignore this
situation.

The problem with strlen actually is that any data type can be treated
as an array of character type. So, if you do 

if(strlen(a) > 0) { changed = 1; a[strlen(a)-1] = '\0'; }

the compiler has to make sure that a != (char*)&changed before it can
decide to call strlen only once. 

Cheers
Tanmoy
--
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