PHP A relatively complete simple file upload_PHP tutorial

$UploadedFile=$_FILES['UploadedFile']['tmp_name'];
$UploadedFile_name=$_FILES['UploadedFile']['name'];
$isTrue=false;
if($UploadedFile)
{
$store_dir=$_SERVER['DOCUMENT_ROOT'];
$accept_overwrite = 1;
$isTrue=true;
}
$fileName = date("YmtHis").$UploadedFile_name;
if (file_exists($store_dir . $fileName))
{
echo "存在相同文件名的文件";
}
$mytype =array(".jpg",".gif",".png");
$filetype=substr($_FILES['UploadedFile']['name'],strrpos($_FILES['UploadedFile']['name'],"."));
$typecount=0;
if($isTrue)
{
for($i=0;$i{
if($filetype==$mytype[$i])
{
$typecount++;
}
}
if($typecount>0)
{
if($_FILES['UploadedFile']['size']<1048576)
{
$b=move_uploaded_file($UploadedFile,$store_dir.$fileName);
if($b)
{
echo "

---

n";
echo "原文件信息：
";
echo "名称:".$_FILES['UploadedFile']['name']."
n";
echo "大小:".$_FILES['UploadedFile']['size']."
n";
echo "类型:".$_FILES['UploadedFile']['type']."
n";
echo "

---

n";
echo "存入数据库的名称为：".$fileName;
echo "

---

n";
}
}
else
{
echo "文件大小不准超过1兆.";
}
}
else
{
echo "不准上传次类型文件！";
}
}
?>