In this tutorial, we will learn How to create a calculator in PHP. In calculator, we will perform simple operations (add, subtract, multiply, divide) with two numbers.
The HTML Code
<div class="signup-form">
<form method="post">
<h2>Calculator</h2>
<p>Developed using PHP</p>
<hr>
<div class="form-group">
<div class="row">
ass="col"><input type="text" class="form-control" name="first_number" placeholder="First Number" required="required" value="<?php echo isset($fn)?$fn:''; ?>" pattern="[0-9]+" title="only numbers"></div>
<div class="col"><input type="text" class="form-control" name="second_number" placeholder="Second Number" required="required" value="<?php echo isset($sn)?$sn:''; ?>" pattern="[0-9]+" title="only numbers"></div>
</div>
</div>
<div class="form-group">
<?php if(isset($result) && is_numeric($result)){?>
<h4 style="color:blue; font-weight:bold;"> Result: <?php echo $result; ?></h4>
<?php } if(isset($error)){?>
<h5 style="color:red; font-weight:bold;">Error: <?php echo $error; ?></h5>
<?php } ?>
</div>
<div class="form-group">
<input class="btn btn-primary" type="submit" name="calculate" value="+">
<input class="btn btn-primary" type="submit" name="calculate" value="-">
</div>
<div class="form-group">
<input class="btn btn-primary" type="submit" name="calculate" value="x">
<input class="btn btn-primary" type="submit" name="calculate" value="/">
</div>
</form>
</div>
PHP Code to perform calculator operations
<?php
if (isset($_POST['Calculate'])) {
$fn=$_POST['first_number'];
$sn=$_POST['second_number'];
$operation=$_POST['calculate'];
if($operation=="/" && ($fn == 0 || $sn == 0)){
$error = "Never divide any number by zero";
}
else{
if($operation=="+")
$result=$fn+$sn;
else if($operation=="-")
$result=$fn -$sn;
else if($operation=="x")
$result=$fn*$sn;
else if($operation=="/")
$result=$fn/$sn;
}
} ?>
Here is the full code that we have written for this calculator
<?php
if (isset($_POST['Calculate'])) {
$fn=$_POST['first_number'];
$sn=$_POST['second_number'];
$operation=$_POST['calculate'];
if($operation=="/" && ($fn == 0 || $sn == 0)){
$error = "Never divide any number by zero";
}
else{
if($operation=="+")
$result=$fn+$sn;
else if($operation=="-")
$result=$fn -$sn;
else if($operation=="x")
$result=$fn*$sn;
else if($operation=="/")
$result=$fn/$sn;
}
} ?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Roboto:400,700">
<title>Calculator in PHP</title>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/css/bootstrap.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="https://code.jquery.com/jquery-3.5.1.min.js"></script>
<script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.0/js/bootstrap.min.js"></script>
<style>
body {
color: #fff;
background: #3598dc;
font-family: 'Roboto', sans-serif;
}
.form-control {
height: 41px;
background: #f2f2f2;
box-shadow: none !important;
border: none;
}
.form-control:focus {
background: #e2e2e2;
}
.form-control, .btn {
border-radius: 3px;
}
.signup-form {
width: 600px;
margin: 30px auto;
}
.signup-form form {
color: #999;
border-radius: 3px;
margin-bottom: 15px;
background: #fff;
box-shadow: 0px 2px 2px rgba(0, 0, 0, 0.3);
padding: 30px;
}
.signup-form h2 {
color: #333;
font-weight: bold;
margin-top: 0;
}
.signup-form hr {
margin: 0 -30px 20px;
}
.signup-form .form-group {
margin-bottom: 20px;
}
.signup-form input[type="checkbox"] {
margin-top: 3px;
}
.signup-form .row div:first-child {
padding-right: 10px;
}
.signup-form .row div:last-child {
padding-left: 10px;
}
.signup-form .btn {
font-size: 16px;
font-weight: bold;
background: #3598dc;
border: none;
min-width: 140px;
}
.signup-form .btn:hover, .signup-form .btn:focus {
background: #2389cd !important;
outline: none;
}
.signup-form a {
color: #fff;
text-decoration: underline;
}
.signup-form a:hover {
text-decoration: none;
}
.signup-form form a {
color: #3598dc;
text-decoration: none;
}
.signup-form form a:hover {
text-decoration: underline;
}
.signup-form .hint-text {
padding-bottom: 15px;
text-align: center;
}
</style>
</head>
<body>
<div class="signup-form">
<form method="post">
<h2>Calculator</h2>
<p>Developed using PHP</p>
<hr>
<div class="form-group">
<div class="row">
<div class="col"><input type="text" class="form-control" name="first_number" placeholder="First Number" required="required" value="<?php echo isset($fn)?$fn:''; ?>" pattern="[0-9]+" title="only numbers"></div>
<div class="col"><input type="text" class="form-control" name="second_number" placeholder="Second Number" required="required" value="<?php echo isset($sn)?$sn:''; ?>" pattern="[0-9]+" title="only numbers"></div>
</div>
</div>
<div class="form-group">
<?php if(isset($result) && is_numeric($result)){?>
<h4 style="color:blue; font-weight:bold;">Result: <?php echo $result; ?></h4>
<?php } if(isset($error)){?>
<h5 style="color:red; font-weight:bold;"> Error: <?php echo $error; ?></h5>
<?php } ?>
</div>
<div class="form-group">
<input class="btn btn-primary" type="submit" name="calculate" value="+">
<input class="btn btn-primary" type="submit" name="calculate" value="-">
</div>
<div class="form-group">
<input class="btn btn-primary" type="submit" name="calculate" value="x">
<input class="btn btn-primary" type="submit" name="calculate" value="/">
</div>
</form>
</div>
</body>
</html>
