use php variable in php file() - php

Question

I have a web site that allows people to upload a csv file and then it loads it into a postgres database. uploading the file is fine and i capture the file name and location ../Data/Uploads/mycsv.csv as $_POST['fname'].
I'm trying to use this variable in $file=file($_POST['fname']) but cant get it to work however if i hard code it in as $file=file("../DATA/Uploads/mycsv.csv") it works. I have attached the code in question. Thanks in advance for any help
Also to clarify echo $_POST['fname']; returns ../DATA/Uploads/mycsv.csv, which is the same as the hard coded value.
please bear with me as im only relatively new to this. I have attached the 2 html forms being used as well. the top one passes the $fname variable containing the file name and path from the php code used to upload the file.
<Form Method="post" Action="../PHP/Loadcsv.php">
<input type="text" value="<?php echo htmlspecialchars($fname);?>" name="fname">
<br />
<Input Type="submit" Value="Continue">
</Form>
this is the php copy the csv into the database
<?PHP
if ($_POST['submit']) {
$file = file(printf($_POST['fname'])); //****doesnt work******
//$file = file("../DATA/Uploads/csv_trial1.csv"); //********This works******
$db = pg_connect("host=localhost dbname=blah user=me password=you");
pg_exec($db, "COPY personaldetails FROM stdin");
foreach ($file as $line) {
$tmp = explode(",", $line);
pg_put_line($db, sprintf("%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\n", $tmp[0], $tmp[1], $tmp[2], $tmp[3], $tmp[4], $tmp[5], $tmp[6], $tmp[7]));
}
pg_put_line($db, "\\.\n");
pg_end_copy($db);
?>
below is the html to run the above php.
<form id='form' method='post' action='' >
<input type="submit" name="submit" />
</form>
after running a whole lot of echo to find where the variable is reaching, i dont think it is reaching the inside of the if statement possibly due to the next use of post??
**update**
So after a little playing and bouncing ideas almost literally off my office walls.... i was on the right track and Devon was right too, my problem was the 2 post requests the answer was to have a php variable $filename = $_POST['fname']; to take the variable from the first form and put this into the input for the second form
<form id='form' method='post' action='' >
<input type="hidden" value="<?php echo htmlspecialchars($filename);?>" name="fname">
<input type="submit" name="submit" />
I'm sure there may be other ways to achieve this but at the moment it works.

Answer 1

I'm not sure where you came up with printf(), but any print or echo command will output the arguments to the browser and won't return it to the function at hand. You don't need to use anything special to use a variable as an argument. Just: file($_POST['fname']);
Printf specifically outputs a formatted string and returns the length of the string. So this is the equivalent of calling file(integer) where integer is the length of $_POST['fname']'s value.