How to delete all file contents in a directory with PHP?

<?php
$dirName = &#39;/www/tmp&#39;;
echo "current :".get_current_user()."  ".$dirName;
deleteDir($dirName);
function deleteDir($dirName){
    if(file_exists($dirName)){//判断目录是否存在
        //如果是目录，那么我们就遍历下面的文件或者目录
        //打开目录句柄
        $dir = opendir($dirName);
        while($fileName = readdir($dir)){
            //不运行像上级目录运行
            if($fileName!="." && $fileName!=".."){
                $file = $dirName."/".$fileName;
                echo "||".$file."||";
                if(is_dir($file)){
                    deleteDir($file);//使用递归删除目录
                }else{
                    echo "--delete-".$file."++";
                    unlink($file);
                }
            }
        }
        closedir($dir);//关闭dir

        if( rmdir( $dirName ) )echo "成功删除目录： $dirName"; 

        
    }else{
        echo "对不起，目录不存在";
    }
}