CGI Example #2

Temperature Converter v2

Formatting added to match the rest of website...
Return to the notes... - Run the program
#!perl -w

#

#  cgi_demo2.pl    (c) Andy Belcher DandyWebDesign 2006

#

#  A simple web-page widget to convert temperatures and demonstrate simple

#  CGI forms. Takes a single input temperature and a unit (F, C or K) and

#  displays the equivalent in all three units.

#  NOTE!  This is a CGI demonstration example intended to show

#  different methods rather than an efficient piece of coding!

#

#  This is the enhanced demo.

#  This one produces a page that matches the rest of the site.

#

################################################################################



#  Pull in required Perl modules

use strict;

use CGI qw(:all);

use CGI::Carp qw(fatalsToBrowser);



#  DECLARE VARIABLES

my $returnurl  = "/tech/cgi/cgi_style.shtml#notes";

my $sourceurl  = "/tech/cgi/cgidemo_source2.html";

my $intemp;

my $inunit;



#  POPULATE OUTPUT SCALARS WITH DEFAULT VALUES FOR DISPLAY

my $outtempc  = 0;

my $outtempk  = 273.15;

my $outtempf  = 32;



#  READ PARAMETERS, FOR EACH PARAMETER USE THE 'param' FUNCTION (PART

#  OF THE CGI MODULE) TO EXTRACT THE ARGUMENTS FROM THE FORM.

#  NOTE THAT IF THE ARGUMENT IS NOT PRESENT $ARG{PARA} IS UNDEFINED

#  NOTE ALSO THAT THE ARGUMENT NAMES MATCH THE FIELD NAMES IN THE FORM

$intemp = param('intemp');

unless((defined($intemp)) && ($intemp)) {$intemp = 0;}

$inunit = param('inunit');

unless((defined($inunit)) && ($inunit)) {$inunit = "C";}



#  PERFORM REQUIRED CALCULATION

if($inunit eq "F")

  {$outtempf  = $intemp;

  $outtempc   = &conv_temp($intemp,"f2c");

  $outtempk   = &conv_temp($outtempc,"c2k");

  }

elsif($inunit eq "K")

  {$outtempk  = $intemp;

  $outtempc   = &conv_temp($intemp,"k2c");

  $outtempf   = &conv_temp($outtempc,"c2f");

  }

else

  {$outtempc  = $intemp;

  $outtempk   = &conv_temp($intemp,"c2k");

  $outtempf   = &conv_temp($intemp,"c2f");

  }



#  OUTPUT PAGE

&do_top;

&do_pathbar;

print "<div id=\"content\">\n";

&do_rightbar;

print<<HERE;

<h2>Perl CGI Demo Program</h2>

<h3>Temperature Converter</h3>

<div id="nextlink"></div><!--nextlink - DHTML loaded -->

<div class="main">

<p>Enter a temperature into the form below and when you submit it the

temperature will be displayed in all three units.</p>

<p><form method="post" action="$ENV{'SCRIPT_NAME'}">

<input type="text" name="intemp" size="5" value="" /> Enter a temperature...

<br /><select name="inunit">

  <option value="C" selected="selected">Celsius</option>

  <option value="F">Fahrenheit</option><option value="K">Kelvins</option>

  </select> Specify the unit of temperature...

<br /><input type="submit" value="Calculate temperatures..." class="button"

  /></form></p>

<table>

<tr><th>Centigrade</th><th>Fahrenheit</th><th>Kelvin</th></tr>

<tr><td>$outtempc</td><td>$outtempf</td><td>$outtempk</td></tr>

</table>

</div><!--main-->

<hr />

<p>Ok, that's the program demo, now click here to return to the <a

  href="$returnurl" title="Return to the documentation for this demo..."

  >documentation page</a> for this demo program...

- <a href="$sourceurl" title="View the source code for this program..."

  >View source code...</a></p>

<script type="text/javascript">doRelatedLinks('cgistyle');//</script>

HERE

  &do_bottom;

#  END PROGRAM



#  SUB-ROUTINES

sub conv_temp

  {my ($in,$un) = @_;

  unless(defined($in)) {$in = 0;}

  if($un eq "f2c")

    {unless($in) {$in = 32;}

    return ($in - 32) * (5/9);

    }

  elsif($un eq "k2c")

    {unless($in) {$in = 273.15;}

    return $in - 273.15;

    }

  elsif($un eq "c2f")

    {unless($in) {$in = 0;}

    return ($in * (9/5)) + 32;

    }

  elsif($un eq "c2k")

    {unless($in) {$in = 0;}

    return $in + 273.15;

    }

  else {return $in;}

  }

#  do_top:  Outputs the topmost part of the webpage

#  Includes the required content-type HEADER line.

#

sub do_top

  {print header;

  print<<HERE;

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

<head>

<title>Dandy Web Design : Techdocs: CGI Applications: Styled CGI Demo...</title>

HERE

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/head.ssi");

  print<<HERE;

</head>

<body>

<div id="navbar">

HERE

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/navbar.ssi");

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/technavbar.ssi");

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/othnavbar.ssi");

  print "</dl></div><!--navbar-->\n";

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/header.ssi");

  }

#

#  do_bottom:  Outputs the bottom section of the webpage

#  Includes 'exit' line as implicit end of processing

#

sub do_bottom

  {print "</div><!--content-->\n";

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/footer.ssi");

  print<<HERE;

</div><!--frame-->

</body>

</html>

HERE

  exit;

  }

#

#  do_rightbar:  Outputs the required right-bar

sub do_rightbar

  {print "<div id=\"rightbar\">\n";

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/bespoke.ssi");

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/cginavlinks.ssi");

  &output_ssi("$ENV{'DOCUMENT_ROOT'}/ssi/cgisrclinks.ssi");

  print "</div><!--rightbar-->\n";

  }

#

#  do_pathbar:    Outputs the path bar

sub do_pathbar

  {print<<HERE;

<div id="pathbar">

<script type="text/javascript">drawPathBar(

  'tech','/tech/tech.shtml','To the Technical pages index...',

  'CGI','/tech/cgi/cgi_index.shtml','To the Perl CGI scripting index...',

  'styling','/tech/cgi/cgi_style.shtml','Making CGI pages match your site...',

  'example2');//</script>

</div><!--pathbar-->

HERE

  }

#

#  output_ssi:  Output from CGI programs goes straight to the browser,

#  it doesn't get parsed again by Apache and so server side includes

#  (SSIs) cannot be used. This function provides SSI functionality to

#  CGI scripts by writing the SSI file content into the output stream.

#  The expected argument is the required SSI file path.



sub output_ssi

  {my $file = $_[0];unless($file) {return;}

  open(SSI,"$file") || die "Cannot open $file for read: $!";

  while(<SSI>) {print $_;}

  close(SSI) || die "Cannot close $file after read: $!";

  }

#  EOF