A Calculator

				
=**************************************
= Name: A Calculator
= Description:This is just a simple Calculator CGI script.
= By: Randy McCleary
=
=This code is copyrighted and has= limited warranties.Please see http://www.Planet-Source-Code.com/vb/scripts/ShowCode.asp?txtCodeId=507&lngWId=6=for details.=**************************************

#!/usr/bin/perl -w
#######################################################################
## This is a simple calculator script written in Perl
## 
##
#######################################################################
use strict;
use CGI qw(:standard);
use CGI::Carp qw(fatalsToBrowser);
	
	
#######################################################################
## Path to the perl script.
my $formname = "calculator.pl";
#######################################################################
	
my $buffer='';
my $value = '';
my @pairs=();
my $pair='';
my $name='';
my ($num1, $num2, $operator) = '';
my %FORM=();
	
print "Content-type: text/html\n\n\n";
if ($ENV{'REQUEST_METHOD'} eq "POST") {
	read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});
}
	
@pairs = split(/&/, $buffer);
foreach $pair (@pairs) {
	($name, $value) = split(/=/, $pair);
	$value =~ tr/+/ /;
	$value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("c", hex($1))/eg;
	$value =~ s/^( +)//;
	$value =~ s/( +)$//;
	$value =~ s/(\t|\r|\n)//g;
	$FORM{$name} = $value;
} # end of foreach
	
$num1 = $FORM{number1};
$num2 = $FORM{number2};
$operator = $FORM{operation};
	
my %opermatch = ('add','+','subtract','-','multiply','*','power','^','divide','/');
	
if ($FORM{status} eq 'calculate') {
	if (ErrorCheck() == 2) {
 		my $answer = GetAnswer();
		print <<_ENDTABLE;
		 <BR>
		 <div align="center"><center>
		 <table border="0" cellspacing="1" width="25%" bgcolor="#C0C0C0">
		 <tr>
		 	 <th colspan="5" bgcolor="#FFFFFF">Answer</th>
		 </tr>
		 <tr>
		 <td width="20%">$num1</td>
		 <td width="20%">$opermatch{$operator}</td>
		 <td width="20%">$num2</td>
		 <td width="20%">=</td>
		 <td width="20%">$answer</td>
		 </tr>
		 </table>
		 </center></div>
_ENDTABLE
	# print "Answer is $answer";
	}
	drawCalc();
}
else { 
 	drawCalc(); 
}
	
print " ";
### end of main body of program ###
sub GetAnswer(){
	my $answer;
	if ($operator eq 'add') { 
		$answer = $num1 + $num2; 
	}
	elsif ($operator eq 'subtract') { 
		$answer = $num1 - $num2; 
	}
	elsif ($operator eq 'multiply') { 
		$answer = $num1 * $num2; 
	}
	elsif ($operator eq 'power') { 
		$answer = PwrFunc(); 
	}
	else { # default is division
		$answer = $num1 / $num2; 
	}
	return $answer;
}
	
sub PwrFunc()
{
	my $total = 1; 
	my $count;
	
	if ($num2 < 0) {
		return 0; 
	} 
	
	if ($num2 == 0) { 
		return 1; 
	} 
	
	for ($count = $num2; $count > 0; $count--){ 
		$total *= $num1; 
	}
	
	return $total;
}
	
sub drawCalc() {
	 print <<__HTML__;
	 <br><br><br>
	 < form method="post" action="$formname">
	 < input type="hidden" name="status" value="calculate">
	 <div align="center"><center>
	 <table border="0" cellspacing="1" cellpadding="0" width="40%" bgcolor="#COCOCO">
	 	<tr>
	 		<td>
	 		 <table border="0" cellspacing="0" cellpadding="5" width="100%" bgcolor="#COCOCO">
	 		 <tr>
	 			<th colspan="4" bgcolor="#FFFFFF">Calculator</th>
	 </tr>
	 <tr>
	 			<td width="25%">< input type="text" name="number1" size="5" maxlength="5"></td>
	 			<td width="25%"><select name="operation" size="1">
				<option selected value="add">+</option>
				<option value="subtract">-</option>
				<option value="multiply">*</option>
				<option value="divide">/</option>
				<option value="power">^</option>
				</select></td>
				<td width="25%">< input type="text" name="number2" size="5" maxlength="5"></td>
				<td width="25%">< input type="submit" value="Enter"></td>
	 		 </tr>
	 		 </table>
	 		</td>
	 </tr>
	 </table>
	 </center></div>
	 </form>
__HTML__
}
	
sub ErrorCheck() {
	if ($num1 eq "" || $num2 eq "") { 
 		ErrorMsg(1); 
 		return 1; 
 	}
	elsif ($num2 == 0 && $operator eq "divide") { 
		ErrorMsg(2); 
		return 1; 
 }
 elsif ($num1 < -999 || $num1 > 999 || $num2 < -999 || $num2 >999){ 
 	ErrorMsg(3); 
 	return 1; 
	}
	else { 
		return 2; 
 	} #no error
}
	
sub ErrorMsg() {
	my ($errornum) = @_;
	my @Errors = ('space filler', 'Missing operand(s)', 'Divide by Zero', 'Improper input values');
	print "<center><br><h3>Error: $Errors[$errornum]</h3></center>";
}