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Full Discussion: Pipe error
Top Forums Programming Pipe error Post 302474157 by Praveen_218 on Tuesday 23rd of November 2010 12:34:54 PM
Old 11-23-2010
Here are some of the errors, you may correct to improve your program ...
Quote:
Originally Posted by beandj
Code:
3include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>

int main(){
 

     int pos;
     char leitor[1000];
     char reader[1000];

    FILE *arq, *arq1, *arq2;
     arq = fopen("teste.txt","r");
        arq1 = fopen("arquivoPai.txt","w+");
        arq2 = fopen("arquivoFilho.txt","w+");


     pipe(fp);
     pipe(pf);
     pid_t pid;
     pid = fork();

    pos = ftell(arq);
       while(!feof(arq))
     {
             if(pid == 0 && (pos%2)==0)
          {
               
               close(fp[0]);
               close(pf[1]);
               read(pf[0], reader, sizeof(reader));
               fprintf(arq1,"%s \n",reader);
               fscanf(arq,"%s",leitor);
               write(fp[1],leitor, (strlen(leitor)+1));
          }
  
             else
          {
  
               close(fp[1]);
               close(pf[0]);
               read(fp[0],reader, sizeof(reader));
               fprintf(arq2,"%s \n",reader);
               fscanf(arq,"%s",leitor);
               write(pf[1],leitor,(strlen(leitor)+1));

          }

      pos = ftell(arq);
     }
 
     exit(0);
     fclose(arq);
     fclose(arq1);
     fclose(arq2);
 

return 0;
}

i dont know how to create a two-way pipes

i need to send father-to-child a pair line of teste.txt
and send child-to-faher a odd line of teste.txt

and i need to print in two diferent .txt

but the program do nothing
There are atleast 3 errors, I could figure out. They are following:

1) You have not declered & defined pf,
2) You have not declered & defined fp,
3) You have not initilize pos; its using a garbage value.

The worst part is that you are controlling the program flow using and AND condition with (pid == 0) && (pos % 2 == 0). You are taking the mod of a garbage value, isn't it?

Now could you please try to analyse the result of that if() expression for the below two cases:
1) When pos has a garbage value which is an odd number,
2) When pos has a garbage value which is an even number

I think its pretty enough for you to know what went wrong.

Also, just declare & define pf and fp as below:
Code:
int pf[2], fp[2];

Rest is okey in your program.
 

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LEARN ABOUT DEBIAN

flarq

FLARQ(1)																  FLARQ(1)

NAME

       flarq - ARQ data transfer utility for fldigi

SYNOPSIS

       flarq [OPTIONS]

DESCRIPTION

       Flarq (fast light automatic repeat request) is a file transfer application that is based on the ARQ specification developed by Paul
       Schmidt, K9PS. It is capable of transmitting and receiving frames of ARQ data via fldigi, as well as MultiPSK on Windows.

OPTIONS

       Long options begin with two hyphens and are handled by flarq. The option names may be abbreviated to any unambiguous substring, and the
       option argument may be separated from the name by a space or equals sign, as per getopt(3).

       Short options begin with a single hyphen and are passed directly to FLTK. They may be abbreviated only as indicated.

       --arq-protocol TYPE
	   Set the ARQ protocol. May be either "fldigi" or "multipsk". Defaults to "fldigi".

       --arq-server-address HOSTNAME
	   Set the ARQ TCP server address. Defaults to "127.0.0.1".  HOSTNAME may be any node name string accepted by getaddrinfo(3).

       --arq-server-port PORT
	   Set the ARQ TCP server port. Defaults to "7322".  PORT may be any service name string accepted by getaddrinfo(3).

       --debug
	   Enable debugging messages.

       --version
	   Print version information and exit.

       --build-info
	   Print build information and exit.

       --help
	   Print options summary and exit.

   Standard FLTK options
       -bg, -background COLOUR
	   Set the background colour.

       -bg2, -background2 COLOUR
	   Set the secondary (text) background colour.

       -di, -display DISPLAY
	   Specifies the X server to connect to; see X(7).

       -dn, -dnd or -nodn, -nodnd
	   Enable or disable drag and drop copy and paste in text fields.

       -fg, -foreground COLOUR
	   Set the foreground colour.

       -g, -geometry GEOMETRY
	   Set the initial window size and position.  Flarq may not honour this option.

       -i, -iconic
	   Start flarq in iconified state.  Flarq may not honour this option.

       -k, -kbd or -nok, -nokbd
	   Enable or disable visible keyboard focus in non-text widgets.

       -na, -name CLASSNAME
	   Set the window class. Defaults to "Flarq".

       -ti, -title WINDOWTITLE
	   Set the window title. Defaults to "flarq - <callsign>".

   Additional UI options
       --font FONT[:SIZE]
	   Set the widget font and (optionally) size. Defaults to "sans:12".

FILES

       $HOME/.flarq
	   The main settings file.

       The following directories are used to interface with MUAs such as Sylpheed:

       $HOME/Mail/ARQin
	   Stores incoming email messages.

       $HOME/Mail/ARQout
	   Stores outgoing email messages.

       $HOME/Mail/ARQsent
	   Stores sent email messages.

       The following directories are used for ARQ file transfer:

       $HOME/ARQrecv
	   Stores received files.

       $HOME/ARQsend
	   Stores files to be transmitted.

       $HOME/ARQfiles/logfile.txt
	   Stores transfer logs.

BUGS

       o   There are no command line arguments to override the default configuration file and ARQ and Mail directories.

SEE ALSO

       fldigi(1), getaddrinfo(3), getopt(3), X(7)

RESOURCES

       Flarq web site: http://www.w1hkj.com/flarq_main.html

       Fldigi web site: http://www.w1hkj.com/Fldigi.html

       BerliOS project page: http://developer.berlios.de/projects/fldigi/

       ARQ specification by Paul Schmidt, K9PS: http://www.w1hkj.com/FlarqHelpFiles/ARQ2.pdf

AUTHORS

       Flarq was written by David Freese, W1HKJ.

       This manual page was written by Stelios Bounanos <sb[at]enotty(dot)net>.

COPYING

       License GPLv3+: GNU GPL version 3 or later.

								    07/01/2012								  FLARQ(1)
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