Convert number to month name in PHP

Just because everyone is using strtotime() and date() functions, I will show DateTime example:

$dt = DateTime::createFromFormat('!m', $result['month']);
echo $dt->format('F');

Use mktime():

<?php
 $monthNum = 5;
 $monthName = date("F", mktime(0, 0, 0, $monthNum, 10));
 echo $monthName; // Output: May
?>

See the PHP manual : http://php.net/mktime

The recommended way to do this:

Nowadays, you should really be using DateTime objects for any date/time math. This requires you to have a PHP version >= 5.2. As shown in Glavić's answer, you can use the following:

$monthNum  = 3;
$dateObj   = DateTime::createFromFormat('!m', $monthNum);
$monthName = $dateObj->format('F'); // March

The ! formatting character is used to reset everything to the Unix epoch. The m format character is the numeric representation of a month, with leading zeroes.

Alternative solution:

If you're using an older PHP version and can't upgrade at the moment, you could this solution. The second parameter of date() function accepts a timestamp, and you could use mktime() to create one, like so:

$monthNum  = 3;
$monthName = date('F', mktime(0, 0, 0, $monthNum, 10)); // March

If you want the 3-letter month name like Mar, change F to M. The list of all available formatting options can be found in the PHP manual documentation.