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.
<?php
$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">
<head>
<meta charset="utf-8" />
<title>Arithmetic calculator</title>
</head>
<body>
<?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>
</select>
<input type ="number" name="nr2" id="nr2" step="any" value=""><br>
<input type ="submit" value="Calculate">
</form>
</body>
</html>
- Results this form:

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which tag is used to add lists into <ul> and <ol> elements?
<dt> <dd> <li>
<ul>
 <li>http://coursesweb.net/html/</li>
 <li>http://coursesweb.net/css/</li>
</ul>
Which value of the "display" property creates a block box for the content and ads a bullet marker?
block list-item inline-block
.some_class {
  display: list-item;
}
Which instruction converts a JavaScript object into a JSON string.
JSON.parse() JSON.stringify eval()
var obj = {
 "courses": ["php", "javascript", "ajax"]
};
var jsonstr = JSON.stringify(obj);
alert(jsonstr);    // {"courses":["php","javascript","ajax"]}
Indicate the PHP class used to work with HTML and XML content in PHP.
stdClass PDO DOMDocument
$strhtml = '<body><div id="dv1">CoursesWeb.net</div></body>';
$dochtml = new DOMDocument();
$dochtml->loadHTML($strhtml);
$elm = $dochtml->getElementById("dv1");
echo $elm->nodeValue;    // CoursesWeb.net
Simple arithmetic calculator in PHP

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