You have not really provided enough detailed information for anyone to be of much help. I assume that you take the input from the user and put it in file.c. If so, are you sure your file.c file is being created and filled properly? Did you add error checking to the system() command and then check the error log for any useful error information? If the system() command is successful, did you check to see if a.out exists (that should be the file created by gcc, IIRC).

When posting to the forum, you need to provide more information about what you have tried, and most importantly, what isn't working. Saying 'but it never works' doesn't tell us nearly enough to help out. We are not psychics :)

Thanks a lot! Here is the original code:

#!/usr/bin/perl
use strict;
use CGI;

print "Content-type: text/plain\n\n";   
my $q=new CGI; 
my $codes=$q->param('c_code');

    my $file = "code.cpp";
    open(FH, ">$file");      ### Must chmod Before writing,
    system("chmod 0777 code.cpp"); ### Can't create and change mode???
+?
    print FH "$codes";
    close(FH); 

&run;

exit(0);

sub run
{
    system("gcc code.cpp"); 

    system("a.out/>result.txt");  
    
    open(F,"result.txt");

    while(<F>)
    {
        print $_,"\n";
    }

    close(F);

}
[download]

Edited by Chady -- added code tags.

Concerning the system command: The environment of the webserver usually is different from that of the ordinary user:
Try executing your Perl programme in the shell of the webserver's user on the target machine and see what happens.
That's closer to what's supposedly to happen, when you execute the code via the webpage.

Now, not concerning the system command, but compiling and running snippets of C code in Perl, you should take a look at Inline::C.

Cheers, Sören

You need to use <tags> to formatt the questions son that they can be read - the code tag is espically imp as i learbt from omitting to use it.

Also I'm new to this (PERL CGI etc), so may have the wrong end of the stick but doubt that you should be giving a file chmod 777 as it is a real network security hazard - i think 755 is used more and is much safer.

my $compileresult = `gcc code.cpp`;
my $aoutresult = `./a.out`;
#... parse aoutresult
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sub run {
  my $cmd_out;
  $cmd_out = `gcc code.cpp`;
  $? and warn $cmd_out;
  print `a.out`; # Note that you had a slash in your call.
  $? and warn "a.out had error";
}
[download]