PHP - File Upload spitting out error - php

Question

I was working on a simple file upload exercise i've gotten from my WebDev Class - We actually only had to copy the code and integrate it to fit our needs.
I tried to do so for my project, sadly it will keep on echoing out the same error.
<?php
$allowed_filetypes = array('.jpg','.gif','.bmp','.png', '.jpeg');
$max_filesize = 524288;
$upload_path = 'uploads/';
$filename = $_FILES['userfile']['name'];
$ext = substr($filename, strpos($filename,'.'), strlen($filename)-1);
var_export($_FILES, $ext);
if(!in_array($ext,$allowed_filetypes))
die('The file you attempted to upload is not allowed.');
if(filesize($_FILES['usrfile']['tmp_name']) > $max_filesize)
die('The file you attempted to upload is too large.');
if(!is_writable($upload_path))
die('You cannot upload to the specified directory, please CHMOD it to 777.');
if(move_uploaded_file($_FILES['usrfile']['tmp_name'],$upload_path . $filename))
echo 'Your file upload was successful, view the file here';
else
echo 'There was an error during the file upload. Please try again.';
?>
It keeps on giving me the 'wrong filetype' error, with all of defined types in the array.
<form id='upload' action="uploadfile.php" method="POST" enctype="multipart/form-data">
<table>
<tr>
<td >Choose a File to Upload</td>
</tr>
<tr>
<td >Select File</td>
<td ><input type="file" name="userfile"></td>
</tr>
<tr>
<td colspan=2 id="sub"><input type="submit" name="submit" value="submit" ></td>
</tr>
</Table>
</form>

Answer 1

$filename = $_FILES['usrfile']['name'];

Answer 2

The 'tmp_name' index contains a temporary file name, not the one the file really had. That's stored in 'name'. See this page for information.
Additionally, you should:
check for errors in the 'error' index.
use pathinfo to get the extension,
lowercase it before searching the array,
add some randomness to the uploaded file name to avoid overwriting existing files.

Answer 3

You can use this as firstly you have to always echo the $_FILES array then start debuging.
change this line from
$allowed_filetypes = array('.jpg','.gif','.bmp','.png', '.jpeg');
to
$allowed_filetypes = array('jpg','gif','bmp','png', 'jpeg');
change the follwing line
if(filesize($_FILES['usrfile']['tmp_name']) > $max_filesize)
to
if(filesize($_FILES['usrfile']['size']) > $max_filesize)
and remove the line
$ext = substr($filename, strpos($filename,'.'), strlen($filename)-1);
and change this line
if(!in_array($ext,$allowed_filetypes))
to
if(!in_array($_FILES['usrfile']['type'],$allowed_filetypes))