Writing c code for who | sort | lp Post: 302118868

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Top Forums Programming Writing c code for who | sort | lp Post 302118868 by the_learner on Thursday 24th of May 2007 05:01:54 PM

05-24-2007

Registered User

Thanks porter..

Does this mean I will need another child-parent processes using fork().. that means another level of if-else ??

Do you mean something like:

Code:

#include <unistd.h>

int main()
{
        int pipe1[2]; /* pipe for:  sort ------> uniq */
        int pipe2[2]; /* pipe for:  uniq ------> wc   */
        int pipe3[2];

        pipe(pipe1);

        if(!fork()) {
                close(1);
                dup(pipe1[1]);
                close(pipe1[0]);
                close(pipe1[1]);
                execlp("sort","sort","work.fp",NULL);
                /* sort failed */
                printf("\n sort failed");

        } else {
                
                pipe(pipe2);

                if (!fork()) {
                        close(0);
                        dup(pipe1[0]);
                        close(1);
                        dup(pipe2[1]);
                        close(pipe1[0]);
                        close(pipe1[1]);
                        close(pipe2[0]);
                        close(pipe2[1]);
                        execlp("uniq","uniq","-c",NULL);
                } else {
                        
                        pipe(pipe3);
                        if (!fork()) {
                                 close(0);
                                 dup(pipe2[0]);
                                 close(1);
                                 dup(pipe3[1]);                                
                                 close(pipe1[0]);
                                 close(pipe1[1]);
                                 close(pipe2[0]);
                                 close(pipe2[1]);
                                 execlp("wc","wc","-l",NULL);
                         } else {
                                 //read from pipe 3
                        }
                }
        }

}

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LEARN ABOUT CENTOS

perl::critic::policy::subroutines::prohibitreturnsort

Perl::Critic::Policy::Subroutines::ProhibitReturnSort(3)User Contributed Perl DocumentatioPerl::Critic::Policy::Subroutines::ProhibitReturnSort(3)

NAME

       Perl::Critic::Policy::Subroutines::ProhibitReturnSort - Behavior of "sort" is not defined if called in scalar context.

AFFILIATION

       This Policy is part of the core Perl::Critic distribution.

DESCRIPTION

       The behavior of the builtin "sort" function is not defined if called in scalar context.	So if you write a subroutine that directly
       "return"s the result of a "sort" operation, then you code will behave unpredictably if someone calls your subroutine in a scalar context.
       This Policy emits a violation if the "return" keyword is directly followed by the "sort" function.  To safely return a sorted list of
       values from a subroutine, you should assign the sorted values to a temporary variable first.  For example:

	  sub frobulate {

	      return sort @list;  # not ok!

	      @sorted_list = sort @list;
	      return @sort	  # ok
	  }

KNOWN BUGS

       This Policy is not sensitive to the "wantarray" function.  So the following code would generate a false violation:

	  sub frobulate {

	      if (wantarray) {
		  return sort @list;
	      }
	      else{
		  return join @list;
	      }
	  }

CONFIGURATION

       This Policy is not configurable except for the standard options.

CREDITS

       This Policy was suggested by Ulrich Wisser and the <http://iis.se> team.

AUTHOR

       Jeffrey Ryan Thalhammer <jeff@imaginative-software.com>

COPYRIGHT

       Copyright (c) 2005-2011 Imaginative Software Systems.  All rights reserved.

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.  The full text of this license
       can be found in the LICENSE file included with this module.

perl v5.16.3							    2014-06-09		  Perl::Critic::Policy::Subroutines::ProhibitReturnSort(3)

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