How to read all files in a specified directory in php?

<code><span><span>function</span><span>treeDirectory</span><span>(<span>$dir</span>)</span>{</span><span>$files</span> = <span>array</span>();
    <span>$dirpath</span> = realpath(<span>$dir</span>);
    <span>$filenames</span> = scandir(<span>$dir</span>);

    <span>foreach</span> (<span>$filenames</span><span>as</span><span>$filename</span>) 
    {
        <span>if</span> (<span>$filename</span>==<span>'.'</span> || <span>$filename</span>==<span>'..'</span>)
        {
            <span>continue</span>;
        }

        <span>$file</span> = <span>$dirpath</span> . DIRECTORY_SEPARATOR . <span>$filename</span>;

        <span>if</span> (is_dir(<span>$file</span>))
        {
            <span>$files</span> = array_merge(<span>$files</span>, <span>self</span>::treeDirectory(<span>$file</span>));
        }
        <span>else</span>
        {
            <span>$files</span>[] = <span>$file</span>;
        }
    }

    <span>return</span><span>$files</span>;
}</code>