Calculator.pl - CGI Application Example

Perl Tutorials - Herong's Tutorial Examples

Dr. Herong Yang, Version 5.10

Perl Tutorials - Herong's Tutorial Examples

∟Calculator.pl - CGI Application Example

This section provides a tutorial example of Perl CGI application: Calculator.pl - Returning the result of any arithmetic expression like a calculator.

Here is a simple CGI application, Calculator.pl:

#- Calculator.pl
#- Copyright (c) 1996 by Dr. Herong Yang, http://www.herongyang.com/
#
   &getValues();
   $res = "";
   $res = eval($exp) if ($exp);
   print "Content-Type: text/html\n\n";
   print "<html><body>\n";
   print "<b>Calculator:</b><br/>\n";
   print "<form action=\"/cgi-bin/Calculator.pl\" methor=\"GET\">\n";
   print "<table border=\"0\">\n";
   print "<tr><td align=\"right\">Expression:</td>\n";
   print "<td><input type=\"text\" name=\"exp\"";
   print   " value=\"$exp\"/></td></tr>\n";
   print "<tr><td align=\"right\">Result:</td>\n";
   print "<td>$res</td></tr>\n";
   print "<tr><td></td>\n";
   print "<td><input type=\"submit\" value=\"Evaluate\"/></td></tr>\n";
   print "</table></form>\n";
   print "</html></body>\n";
   exit;   
sub getValues {
   $query = $ENV{'QUERY_STRING'};
   @list = split( /\&/, $query);
   foreach (@list) {
      ($var, $val) = split(/=/);
      $val =~ s/\'//g;
      $val =~ s/\+/ /g;
      $val =~ s/%(\w\w)/sprintf("%c", hex($1))/ge;
      $exp = $val if ($var =~ /exp/);
   }
}

Enjoy it.

Table of Contents

About This Book

Perl on Linux Systems

ActivePerl on Windows Systems

Data Types: Values and Variables

Expressions, Operations and Simple Statements

User Defined Subroutines

Perl Built-in Debugger

Name Spaces and Perl Module Files

Symbolic (or Soft) References

Hard References - Addresses of Memory Objects