Determine the area by IP address. Determine the correctness of the IP address. How to judge the correctness of the IP address. How to judge the IP address type.

<code><span>//获取用户真实IP</span>
    public function get_client_ip() {
        <span>if</span> (<span>getenv</span>(<span>"HTTP_CLIENT_IP"</span>) && strcasecmp(<span>getenv</span>(<span>"HTTP_CLIENT_IP"</span>), <span>"unknown"</span>))
            <span>$ip</span> = <span>getenv</span>(<span>"HTTP_CLIENT_IP"</span>);
        <span>else</span><span>if</span> (<span>getenv</span>(<span>"HTTP_X_FORWARDED_FOR"</span>) && strcasecmp(<span>getenv</span>(<span>"HTTP_X_FORWARDED_FOR"</span>), <span>"unknown"</span>))
            <span>$ip</span> = <span>getenv</span>(<span>"HTTP_X_FORWARDED_FOR"</span>);
        <span>else</span><span>if</span> (<span>getenv</span>(<span>"REMOTE_ADDR"</span>) && strcasecmp(<span>getenv</span>(<span>"REMOTE_ADDR"</span>), <span>"unknown"</span>))
            <span>$ip</span> = <span>getenv</span>(<span>"REMOTE_ADDR"</span>);
        <span>else</span><span>if</span> (isset (<span>$_SERVER</span>[<span>'REMOTE_ADDR'</span>]) && <span>$_SERVER</span>[<span>'REMOTE_ADDR'</span>] && strcasecmp(<span>$_SERVER</span>[<span>'REMOTE_ADDR'</span>], <span>"unknown"</span>))
            <span>$ip</span> = <span>$_SERVER</span>[<span>'REMOTE_ADDR'</span>];
        <span>else</span><span>$ip</span> = <span>"unknown"</span>;
        <span>return</span> (<span>$ip</span>);
    }

    <span>// 调用get_client_ip方法</span><span>$ip</span> = <span>$this</span>->get_client_ip();
    <span>// 调用淘宝接口</span><span>$url</span> = <span>"http://ip.taobao.com/service/getIpInfo.php?ip="</span>.<span>$ip</span>;
    <span>$dip</span> = file_get_contents(<span>$url</span>);
    <span>$dd</span> = json_decode(<span>$dip</span>,true);
    var_dump(<span>$dd</span>);</code>

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The above introduces how to determine the area by IP address, including IP address and determination. I hope it will be helpful to friends who are interested in PHP tutorials.