PHP: Remove all characters from a string except numerical digit

You can use following example for removing character leaving all the numerical digit

$nano_number=preg_replace('/[^0-9.]/', '', $nano_string);

PHP : Short format of starting and ending scope

To use short format of  starting and ending scope in PHP like <? echo "Hello"; ?>
we have to change the paarmeter
short_open_tag=On

from /etc/php.ini file.

If we use short_open_tag=Off, we have to use  <?php  echo "Hello"; ?> .