Php file upload system note

It's a note. In fact, the entire program has been written, although a little ugly, but it's okay .. after all, it is the first program written by myself... the whole system only uses PHP with codes, no JS, no regular expressions... pure PHP... in fact, I will not...
Below is the html code of the original form...
Upload file Form
The code is as follows:


In the form, enctype = "multipart/form-data" indicates the MIME encoding of the form. By default, the encoding format is application/x-www-form-urlencoded and cannot be used for file upload. only multipart/form-data can be used to completely transmit file data, perform the following operations. enctype = "multipart/form-data" is used to upload binary data. the values in form are passed in a binary stream.
This sentence seems useless... I thought this could limit the size of the uploaded file. The size of the uploaded file is only in php. in ini or in the script of the file to be uploaded later, you have set up... in my program, php is directly set. in ini, upload_max_filesize = 6 m.
Below is the upload program
Code
The code is as follows:
$ Uploaddir = "./map /";
$ Typearr = array ("rar", "zip", "w3m", "w3x ");
$ Findstr = array ("/", "\", "", "<", ">"); // filter the name
$ Mapname = str_replace ($ findstr, '', ($ _ POST ['mapname']);
// Get the extension
Function upfiletype ($ filename ){
$ Arr = explode ('.', $ filename );
$ A = count ($ arr)-1;
Return $ arr [$ a];
}
// Whether the string is a pure number
Function isNo ($ str ){
$ Intarr = array ('1', '2', '3', '4', '5', '6', '7', '8 ', '9', '0 ','. ');
$ A = str_replace ($ intarr, '', $ str );
Return ($ a = "")? 1:0;
}
///// Control the window size ///////
Function html (){
Echo <
File Upload

Script
Function ResetSize (){
Self. resizeTo (300,300)
Self. moveTo (300,200)
}
Script


Eof;
}
If (isNo ($ mapname )){
Html ();
Exit ('Enter the correct map name ');
}
// Determine whether a file is uploaded
If (! Is_uploaded_file ($ _ FILES ['map'] ['tmp _ name']) {
Html ();
Exit ("You have not uploaded a file or uploaded a file larger than 6 MB ");
}
// Determine whether the upload is repeated
$ Clintfilename = str_replace ($ findstr, '', $ _ FILES ['map'] ['name']);
If (isset ($ _ COOKIE ['upload']) {
Foreach ($ _ COOKIE ['upload'] as $ value ){
If ($ value = $ clintfilename ){
Html ();
Exit ("Please do not upload again ");
}
}
}
$ Filetype = strtolower (upfiletype ($ _ FILES ['map'] ['name']);
If (! In_array ($ filetype, $ typearr )){
Html ();
Exit ("please upload the correct map file, supporting rar, zip, w3m, w3x ");
}
// Determine whether the server file exists
$ Filename = $ mapname. '.'. $ filetype;
For ($ a = 1; $ fopen = @ fopen ($ uploaddir. $ filename), "r"); $ a ++ ){
$ Filename = $ mapname. "$ a". '.'. $ filetype;
Fclose ($ fopen );
}
// Start file transfer;
$ Filepath = $ uploaddir. $ filename;
If (move_uploaded_file ($ _ FILES ['map'] ['tmp _ name'], $ filepath )){
// Set a cookie to see if duplicate uploads exist.
Setcookie ("upload []", $ clintfilename, time () + 60*12 );
Html ();
Echo "uploaded successfully ";
$ Log = fopen ("upload. log", "a7 ");
$ Logtxt = date ("Ymd "). "| ". date ("H: I "). "| ". $ _ SERVER ["REMOTE_ADDR"]. "| ". $ filename. "\ r \ n ";
Fwrite ($ log, $ logtxt );
}
?>

Because it was the first time to write... there were problems in many places, and it was changed when I was writing...