上传文件的功能是各类站点的基本功能，但是网络上也存在一些用心不良的人伪装图片或其他文件，上传一些木马或病毒到服务器上。普通php函数文件类型函数无法正确识别，安全的做法应该是头文件判断：

";
echo "gif:".checkTitle('img/weather.gif')."
";
echo "gif:".checkTitle('img/7768752.gif')."
";
echo "gif:".checkTitle('img/gif001.gif')."
";
echo "gif:".checkTitle('img/gif002.gif')."
";
echo "gif:".checkTitle('img/gif007.gif')."
";
echo "jpeg:".checkTitle('img/weather.jpg')."
";
echo "jpeg:".checkTitle('img/0001.jpg')."
";
echo "jpeg:".checkTitle('img/1.jpg')."
";
echo "jpeg:".checkTitle('img/0002.jpg')."
";
echo "jpeg:".checkTitle('img/4.jpg')."
";
echo "jpeg:".checkTitle('img/5.jpg')."
";
echo "jpeg:".checkTitle('img/71885.jpg')."
";
echo "jpeg:".checkTitle('img/imgad.jpg')."
";
echo "png:".checkTitle('img/weather.png')."
";
echo "png:".checkTitle('img/1.png')."
";
echo "png:".checkTitle('img/2.png')."
";
echo "png:".checkTitle('img/3.png')."
";
echo "png:".checkTitle('img/4.png')."
";
echo "png:".checkTitle('img/5.png')."
";
echo hexdec(89)."
";
echo hexdec(50)."
";
//6072,102119
?>