PHP code to recursively list all files and directories_PHP tutorial

/*My program is on SREVER abroad. It is difficult for me to remember where the program I wrote is stored.
So I compiled a simple directory recursive function and it is very convenient to view my program.
*/
function tree($directory)
{
$mydir=dir($directory);
echo "

";
while($file=$ mydir->read()){
if((is_dir("$directory/$file")) AND ($file!=".") AND ($file!="..")){
echo "
• $file
";
tree("$directory/ $file");
}else{
echo "
• $file
";
}
}
echo "

The directory is pink