Four php codes to obtain file extension_PHP tutorial

Three php tutorial codes for obtaining file extensions

//Method 1:
function extend_1($file_name)
{
$retval="";
$pt=strrpos($file_name, ".");
if ($pt) $retval=substr($file_name, $pt+1, strlen($file_name) - $pt);
return ($retval);
}

//Method 2
php code

function extend_2($file_name)
{
$extend = pathinfo($file_name);
$extend = strtolower($extend["extension"]);
return $extend;
}
function extend_2($file_name) { $extend = pathinfo($file_name); $extend = strtolower($extend["extension"]); return $extend; }

//Method 3
php code

function extend_3($file_name)
{
$extend =explode("." , $file_name);
$va=count($extend)-1;
return $extend[$va];
}
function extend_3($file_name) { $extend =explode("." , $file_name); $va=count($extend)-1; return $extend[$va]; }

//Method 4
php code

function getfileext($file_name)
{
while($dot = strpos($file_name, "."))
{
$file_name = substr($file_name, $dot+1);
}
return $file_name;
}
?>
function getfileext($file_name) { while($dot = strpos($file_name, ".")) { $file_name = substr($file_name, $dot+1); } return $file_name; } ?>