一个简单的上传文件页面
<HTML>
<HEAD>
<TITLE> 作业提交 </TITLE>
</HEAD>
<?
//上载文件
if (($submitup!="")&&($uploadfile!="")&&($uploadfile!="none"))
{
if (copy($uploadfile,$uploadfile_name))
echo "<script>alert('上传文件",$uploadfile_name,"成功!')</script>";
else
echo "<script>alert('上传文件",$uploadfile_name,"失败')</script>";
}
?>
<FORM enctype="multipart/form-data" METHOD="post" ACTION="<? echo $PHP_SELF; ?>">
<INPUT TYPE="hidden" name="MAX_FILE_SIZE" value=5000>
请输入要提交作业的文件名:<BR>
<INPUT TYPE="file" NAME="uploadfile" size=50 >
<INPUT TYPE="submit" value="提交作业" name="submitup">
</FORM>
</BODY>
</HTML>
///////////////////////////
请问这句 if (($submitup!="")&&($uploadfile!="")&&($uploadfile!="none"))
$uploadfile!=""和$uploadfile!="none"有什么不同吗?