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Re: main return value is helpfull?

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supercat@casperkitty.com wrote:

> On Sunday, April 16, 2017 at 2:51:24 PM UTC-5, esmaeel ensanimehr wrote:
>> but is there any useful example for main() return value?
>> 
>> for example:
>> int c = main();
> 
> Many environments from which C programs can be run provide a means via
> which
> they can indicate success or failure to the calling process.  When running
> a sequence of programs via shell script (Unix), batch file (DOS/Windows),
> or other such means, it can be helpful to have the process stop as soon as
> any part of it fails. 
[snip]
> In Unix, the default
> behavior would from what I understand be to stop script processing if any
> program returns a non-zero value *unless* a special syntax is used to
> indicate that errors should not terminate processing.

Nonsense.

Unix shell scripting languages have a well-defined behaviour wrt evaluating 
the return value from a process.
1) Unless explicitly tested, the return value (no matter what it is) is
   ignored.
2) When explicitly tested, a return value of zero (0) is treated as an
   indication of success. A non-zero value is /not/ an explicit indication
   of failure.

3) The script may test for a specific return value, and take action
   accordingly.


Consequently, the following is valid...

  cat >test_1.c <<EOF
  int main(void) { return 0; }
  EOF
  if cc -o test_1 test_1.c
  then
    test_1
  else
    echo Compilation returned a non-zero rc
  fi

where cat, cc, and test_1 are all programs that return "return values" to 
the script.

[snip]

-- 
Lew Pitcher
"In Skills, We Trust"
PGP public key available upon request

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Thread

main return value is helpfull? esmaeel ensanimehr <eensanimehr@gmail.com> - 2017-04-16 12:51 -0700
  Re: main return value is helpfull? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-16 21:11 +0100
  Re: main return value is helpfull? supercat@casperkitty.com - 2017-04-16 13:19 -0700
    Re: main return value is helpfull? Keith Thompson <kst-u@mib.org> - 2017-04-16 14:41 -0700
      Re: main return value is helpfull? Andrey Tarasevich <andreytarasevich@hotmail.com> - 2017-04-16 18:58 -0700
    Re: main return value is helpfull? Manfred <noname@invalid.add> - 2017-04-17 19:34 +0200
    Re: main return value is helpfull? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2017-04-17 13:57 -0400
      Re: main return value is helpfull? Keith Thompson <kst-u@mib.org> - 2017-04-17 12:19 -0700
        Re: main return value is helpfull? Manfred <noname@invalid.add> - 2017-04-18 13:03 +0200
          Re: main return value is helpfull? Keith Thompson <kst-u@mib.org> - 2017-04-18 09:29 -0700
  Re: main return value is helpfull? gordonb.xo0e7@burditt.org (Gordon Burditt) - 2017-04-17 04:40 -0500
  Re: main return value is helpfull? Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2017-04-18 21:39 -0600

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