PHP

Checking a Valid Number

You want to ensure that a variable conatins a number, even if it's typed as a string. Alternatively, you want to check if a variable is not only a number, but is also specifically typed as a one.

Use is_numeric() function to discover whether a variable contains a number.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="EN" lang="EN">
<head>
<title>Checking a Valid Number</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
$num = 5;
$output = is_numeric($num);
echo "Is $num numeric? $output<br />";
$num = '5';
$output = is_numeric($num);
echo "Is $num numeric? $output<br />";
$num = "05";
$output = is_numeric($num);
echo "Is $num numeric? $output<br />";
$num = 'five';
$output = is_numeric($num);
echo "Is $num numeric? $output<br />";
$num = 0xDECAFBAD;
$output = is_numeric($num);
echo "Is $num numeric? $output<br />";
$num = "10e200";
$output = is_numeric($num);
echo "Is $num numeric? $output<br />";
?>
</p>
</body>
</html>

View the effect