How to convert text in php?

Question

PHP

$A = $value;
echo $A;  //покажет Alfa Romeo

You need to echo the converted text so that it looks like this (lowercase characters and underscore if more than one word):
echo $A; //покажет alfa_romeo, но не Alfa Romeo

Answer 1

<?
function f($str)
{
  return strtolower(str_replace(' ', '_', $str));
}
echo f('Alfa Romeo');
?>