Create Basic Calculator in PHP

by Sam  

One of the most common exercises we encounter in computer programming is basic calculator. That’s why, I posted this exercise for PHP beginners.

Below are the functionalities about the source code:

  • Display the result of first and second number based on the operation submitted.
  • Check if first and second numbers are not empty.
  • In division, it is invalid to directly divide a number by Zero. Hence, we need to validate it first and display an error message if the divisor is zero.

<!DOCTYPE html>
<title>Basic Calculator</title>
if( isset($_POST['fnum']) && isset($_POST['snum']) )
$fnum = $_POST['fnum']
$snum = $_POST['snum'];
if( $fnum != "" && $snum != "")
if( isset($_POST['add']) ){
echo "The Sum is : " . ($fnum + $snum);
}elseif( isset($_POST['subtract']) ){
echo "The Difference is : " . ($fnum - $snum);
}elseif( isset($_POST['multiply']) ){
echo "The Product is : " . ($fnum * $snum);
}elseif( isset($_POST['divide']) ){
if( $snum == 0)
echo "Error: Cannot divide by Zero";
echo "The Quotient is : " . ($fnum / $snum);
<h2>Basic Calculator</h2>
<form action="" method="POST">
<td>Enter First number : </td>
<td><input type="text" name="fnum"></td>
<td>Enter Second number : </td>
<td><input type="text" name="snum"></td>
<input type="submit" name="add" value="Add">&nbsp;
<input type="submit" name="subtract" value="Subtract">&nbsp;
<input type="submit" name="multiply" value="Multiply">&nbsp;
<input type="submit" name="divide" value="Divide">

If you have questions, feel free to comment below.

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