<!DOCTYPE html>
<html>
 <head>
  <meta charset="UTF-8">
  <title> calculator </title>
 </head>
 <body bgcolor="goldenrod">
<center>
<h1>Calculator Application</h1>
<form action="projectcal.php" method="POST">
Type value1:<br/><input type="text" name="value1"><br/><br/>
Type value2:<br/><input type="text" name="value2"><br/><br/>
Calculation sign:<br/><input type="text" name="action"><br/><br/>
<input type="submit" name="submit" value="Submit">
</form>
</center>
above..created html form for putting the value...and below is the source code..
<?php
if(isset($_POST['submit']))
{   
storing in local var
  $value_1=$_POST['value1'];
  $value_2=$_POST['value2'];
  $action=$_POST['action'];
}         
if($value_1=='' || $value_2=='')                //errorline
{
   echo "<script>alert('Please Enter Any Value')</script>";   //if user enters blank value
   exit();
   }
   if($action=='')
   {
    echo "<script>alert('Please Enter the Operator Sign')</script>"; 
   }  
using array for shorter code
   if(in_array($action,array('+','-','*','/')))     
if user enters any of the the above sign in action field..than it will echo the value....and i am getting the result by using this ...but error is not going from line 29
   switch($action)
    {  
     case '+': 
       echo "Your answer is ";   
       echo $value_1+$value_2;
     break;
     case '-': 
       echo "Your answer is ";
       echo $value_1-$value_2;
     break;
     case '*':
       echo "Your answer is ";
       echo $value_1*$value_2;
     break;
     case '/':
       echo "Your answer is ";
       echo $value_1/$value_2;
     break;   
  }
 ?>
</body>
</html>
hope its clear now
 
    