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Groups > comp.lang.c > #109590
| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: solved Re: obtaining a c value from a perl script |
| Date | 2017-05-09 15:06 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <874lwuazve.fsf@bsb.me.uk> (permalink) |
| References | (5 earlier) <lnd1bqexzs.fsf@kst-u.example.com> <01776996-90c9-4721-ab10-ab6149d828fa@googlegroups.com> <enat1jFqnvhU1@mid.individual.net> <32cc7dc7-4419-44a3-b0f5-50d1a7f0d400@googlegroups.com> <endhaeFbvqgU1@mid.individual.net> |
fred flintstone <fred@server.invalid> writes:
> On 05/08/2017 04:39 AM, Malcolm McLean wrote:
<snip>
>> When declaring a function that accepts a function pointer in C, it is good
>> practice to always add a void * as a parameter, and accept a void * to pass
>> back.
<snip>
> Thanks for your elaboration, malcolm, it prompted the literal solution
> of this thread.
You may have misunderstood. Your code has no functions that meet the
criteria in Malcolm's remark: "a function that accepts a function
pointer".
<snip>
> This program was called with "./jup".
> Value from perl : 2457987.259259
> Can't use an undefined value as a SCALAR reference at 3.neptune.pl line 102.
> $
>
> #include <stdio.h>
> #include <stdlib.h>
>
> int main (int argc, char *argv[])
> {
> double d;
> printf ("This program was called with \"%s\".\n",argv[0]);
> if (argc == 2)
> {
> d = atof(argv[1]);
> printf("Value from perl : %f\n", d );
> char array[20] = "Hello from C";
> return ( array );
You compiler should have told you that this was, at best, dodgy. main
is an int valued function and 'array' is not an int.
Just as you are choosing to pass the number to your program as a string,
you need to get the results back as a string. To do that you *print*
the result:
#include <stdio.h>
#include <stdlib.h>
int main (int argc, char *argv[])
{
if (argc == 2)
printf("%f\n", atof(argv[1]) / 2);
else fprintf(stderr, "Error: 1 argument expected.\n");
return 0;
}
and in Perl you collect this output for later use:
$ perl -e 'print "C program returns ", `./jup 22`;'
C program returns 11.000000
<snip>
--
Ben.
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obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-04-30 04:36 -0700
Re: obtaining a c value from a perl script Noob <root@127.0.0.1> - 2017-04-30 14:48 +0200
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-01 02:25 -0700
Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-01 08:46 -0700
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-03 02:12 -0700
Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-03 11:48 +0100
Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-04-30 16:16 +0100
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-01 04:18 -0700
Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-01 13:41 +0100
Re: obtaining a c value from a perl script Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2017-05-03 05:10 -0700
Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-03 15:00 +0100
Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-03 08:55 -0700
Re: obtaining a c value from a perl script Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2017-05-03 09:02 -0700
Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-03 17:22 +0100
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-08 01:43 -0700
Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-08 09:06 -0700
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-09 00:35 -0700
Re: obtaining a c value from a perl script David Brown <david.brown@hesbynett.no> - 2017-05-09 13:59 +0200
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-08 02:45 -0700
Re: obtaining a c value from a perl script Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2017-05-08 04:39 -0700
solved Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-09 02:43 -0700
Re: solved Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-09 15:06 +0100
Re: solved Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-10 01:03 -0700
Re: solved Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-10 11:18 +0100
Re: solved Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-12 02:26 -0700
Re: solved Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-12 11:51 +0100
Re: solved Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-12 03:49 -0700
Re: solved Re: obtaining a c value from a perl script Manfred <invalid@invalid.add> - 2017-05-10 23:21 +0200
Re: solved Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-10 16:23 -0700
Re: solved Re: obtaining a c value from a perl script Robert Wessel <robertwessel2@yahoo.com> - 2017-05-11 15:57 -0500
Re: solved Re: obtaining a c value from a perl script Jerry Stuckle <jstucklex@attglobal.net> - 2017-05-11 18:57 -0400
Re: solved Re: obtaining a c value from a perl script Robert Wessel <robertwessel2@yahoo.com> - 2017-05-11 18:38 -0500
Re: solved Re: obtaining a c value from a perl script Robert Wessel <robertwessel2@yahoo.com> - 2017-05-11 18:46 -0500
Re: solved Re: obtaining a c value from a perl script Jerry Stuckle <jstucklex@attglobal.net> - 2017-05-11 21:11 -0400
Re: solved Re: obtaining a c value from a perl script Robert Wessel <robertwessel2@yahoo.com> - 2017-05-12 01:51 -0500
Re: solved Re: obtaining a c value from a perl script Jerry Stuckle <jstucklex@attglobal.net> - 2017-05-14 23:49 -0400
Re: obtaining a c value from a perl script Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-09 07:46 -0700
Re: obtaining a c value from a perl script mark.bluemel@gmail.com - 2017-05-03 09:06 -0700
Re: obtaining a c value from a perl script gazelle@shell.xmission.com (Kenny McCormack) - 2017-05-03 17:02 +0000
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-08 01:51 -0700
Re: obtaining a c value from a perl script Manfred <noname@invalid.add> - 2017-05-04 18:21 +0200
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-08 03:52 -0700
Re: obtaining a c value from a perl script Jerry Stuckle <jstucklex@attglobal.net> - 2017-05-08 08:38 -0400
Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-08 09:14 -0700
Re: obtaining a c value from a perl script "James R. Kuyper" <jameskuyper@verizon.net> - 2017-05-08 12:17 -0400
Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-08 09:26 -0700
Re: obtaining a c value from a perl script jameskuyper@verizon.net - 2017-05-08 11:02 -0700
Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-08 11:39 -0700
Re: obtaining a c value from a perl script Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-09 07:16 -0700
Re: obtaining a c value from a perl script Keith Thompson <kst-u@mib.org> - 2017-05-09 08:18 -0700
Re: obtaining a c value from a perl script fred flintstone <fred@server.invalid> - 2017-05-10 00:29 -0700
Re: obtaining a c value from a perl script Tim Rentsch <txr@alumni.caltech.edu> - 2017-05-10 05:26 -0700
Re: obtaining a c value from a perl script Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-05-08 18:20 +0100
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