Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!mailrus!wuarchive!texbell!vector!attctc!bobc
From: bobc@attctc.Dallas.TX.US (Bob Calbridge)
Newsgroups: comp.lang.c
Subject: evaluation order
Keywords: which way
Message-ID: <9361@attctc.Dallas.TX.US>
Date: 14 Sep 89 00:51:45 GMT
Distribution: na
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 26

Is there any way to guarantee the order in which certain functions are
evaluated?  By way of example, if I wanted to avoid the replication of 
of strlen() in the following example:

if (write(handle, buf, strlen(buf)) != strlen(buf)) do_something();

by using rephrasing it like:

if (write(handle, buf, len=strlen(buf)) != len) do_something();

can I be assured that 'len' will be assigned the length of 'buf' before it
is used on the right side of the comparison operator.  I understand that
some optimizing compilers may do some odd re-arranging and I'm worried that
the value of 'len' before excuting this line of code may be used on the
right side.  Is this really possible?  Are there any assurances?

I know that I can try this with my compiler and some test code but would it
be portable?

thanks,
Bob
-- 
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=             I know it's petty..........                                     =
-                  But I have to justify my salary!                           -
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