Subdirectory php code to change the suffix of all files in the directory and subdirectories

I don't deal with files very often, so I'm not very familiar with directory traversal. I searched for information and modified it myself.
Let everyone see if it needs to be improved
The main purpose of the code is to change the file suffix in batches. Since the Taobao data package image types are different, it needs to be changed to suit the needs.

Copy the code The code is as follows:

//This file and the file in the directory to be changed are placed in the same folder
define("STA",".gif"); //Original file format
define("END",".jpg"); //Format to be changed
$dir="./";
$arr=allfile($dir);
foreach($arr as $t)
{
$t=str_replace(".//","",$t);
if(substr_count($t,STA)>0)
{
$f2=str_replace(STA,"" ,$t);
rename($t,$f2.END);
}
}
//Function to get all files in the directory
function allfile($dir)
{
$files=array();
if (is_file($dir))
{
return $dir;
}
$handle = opendir($dir);
if($handle) {
while(false !== ($file = readdir($handle)) ) {
if ($file != '.' && $file != '..') {
$filename = $dir . "/" . $file;
if(is_file($filename)) {
$files [] = $filename;
}else {
$files = array_merge($files, allfile($filename));
}
}
} // end while
closedir($handle);
}
return $files;
}
?>

The above introduces the subdirectory PHP code to change the directory and all file suffixes in the subdirectory, including the content of the subdirectory. I hope it will be helpful to friends who are interested in PHP tutorials.