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Uploading files in PHP

by: Saif
|
June 10, 2003

Think of an application where you want your users to upload files to your machine. Uploading files in PHP is very easy. You can upload any type of file from client to server. Files are uploaded from the browser using an "input" tag, set the type parameter in the "input" tag as "File". This is supported by all popular browsers currently available on the market. Important thing is to set the ENCTYPE attribute of the form to "multipart/form-data" and set the form's action element to the file upload page. The file upload page will handle the file uploading. Here is the code:

Create a simple html form for submitting the file:


<form action="myupload.php" method=post enctype="multipart/form-data">
submit this file: <input type=file name="userfile" size="20">
<input type=submit>
</form>

Now, create a php file named as "myupload.php":


<?
if(!empty($userfile)) {
 
//copy the file to some permanent location
copy($userfile, "/php/www/files/myfile.txt");

//destroy the file
unlink($userfile);

//display message
echo("file uploaded");
}
?>

Details:

Handling uploaded file is very easy in PHP. First, the file is saved in the temporary directory of your operating system (if you have not set the path to your own temporary directory in the php.ini file). You can copy the uploaded file from the temporary directory to the location of your choice. The file in the temporary directory is automatically destroyed at the end of the request. File name is accessible in the same way as all form data. In our code, we have set the name for the uploaded file as "userfile". You can access this variable in the upload file page as $userfile. We copy the file to a permanent location using the copy() function. Although, the uploaded file is automatically destroyed at the end of the request but its a good practice to destroy the file explicitly. You can use the unlink() function to destroy the file.

You can check if the file has been uploaded to the server using different attributes provided by the PHP. For example, if you dont want to allow your users to upload the same file again and again, you can put a restriction on the user to upload new files only. We can set limit on the size of the file to be uploaded by adding an <input size="20"> element with the NAME attribute set to MAX_FILE_SIZE and the VALUE to the upper limit. I havent demonstrated this in my sample code but here the piece of code for your reference:

<input type=hidden name=MAX_FILE_SIZE value=1024> <input type=file name=userfile>

Remember, the hidden <input size="20"> tag should precede the file <input size="20"> tag.

Place a check before displaying a message, use the empty() function to check if $userfile variable contains something or not, if its empty then display the message telling the user that the file hasn't been uploaded otherwise display the message that the file has been uploaded successfully.

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