The code from this page shows how to make a simple arithmetic calculator in PHP with the basic operators (addition, subtraction, multiplication, division), using a html form and a simple php script.
- Click on the code to select it.
$res =''; //store the outputed value (added in html)

//if required form data submitted
if(isset($_POST['nr1']) && isset($_POST['nr2']) && isset($_POST['opr'])){
 //get form data
 $nr1 = floatval($_POST['nr1']);
 $nr2 = floatval($_POST['nr2']);
 $opr = trim(strip_tags($_POST['opr']));

 //calculate according to $opr
 if($opr =='+') $res = $nr1 + $nr2;
 else if($opr =='-') $res = $nr1 - $nr2;
 else if($opr =='*') $res = $nr1 * $nr2;
 else if($opr =='/') $res = $nr1 / $nr2;

 $res = $nr1 .' '. $opr .' '. $nr2 .' = '. number_format($res, 2);
<!doctype html>
<html lang="en">
<meta charset="utf-8" />
<title>Arithmetic calculator</title>
<?php echo $res; ?>
<form action="" method="post">
<input type ="number" name="nr1" id="nr1" step="any" value="0">
<select name="opr" id="opr">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
<input type ="number" name="nr2" id="nr2" step="any" value=""><br>
<input type ="submit" value="Calculate">
- Results this form:

Daily Test with Code Example

Which tag renders as emphasized text, displaying the text oblique?
<strong> <pre> <em>
<p>Web development courses: <em></em></p>
Which CSS property defines the space between the element border and its content?
margin padding position
h3 {
  padding: 2px 0.2em;
Click on the method which returns the first element that matches a specified group of selectors.
getElementsByName() querySelector() querySelectorAll()
// gets first Div with class="cls", and shows its content
var elm = document.querySelector("div.cls");
Indicate the PHP variable that contains data from a form sent with method="post".
if(isset($_POST["field"])) {
  echo $_POST["field"];
Simple arithmetic calculator in PHP

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