What's wrong with my If-statement to check uploaded file? (PHP)

Question

I am trying to test if the uploaded file is the image type I want. If it isn't a gif,jpeg, png, it should echo "Problem". But when I execute this code, it always says there's a problem. What's wrong with my if statement?

$uploadfile_type=$_FILES['userfile']['type'];

    if ( ($uploadfile_type !='image/gif') || ($uploadfile_type !='image/jpeg') 
    || ($uploadfile_type !='image/png'))  
    {
        echo 'Problem: file is not a gif or jpeg or png!';
        exit;
    }

This code works when I am only checking one type of image. Ex: if($uploadfile_type !='image/gif') --> this statement would work but when I add a OR it doesn't.

Answer 1

You're using OR (||) when you should be using AND (&&). You want to say there's a problem if it's not a GIF and it's not a JPG and it's not a PNG. With OR, the only way it wouldn't say there was a problem is if you had some sort of file that managed to be all 3 types at once.

Answer 2

You need to use AND instead of OR:

if ( ($uploadfile_type !='image/gif') && ($uploadfile_type !='image/jpeg')
  && ($uploadfile_type !='image/png'))  

OR will always fail since a file will only ever be of a single type.

Answer 3

Chad's answer is right.

If you want to shorten the code and make it prettier:

if (!in_array($uploadfile_type, array('image/gif', 'image/jpeg', 'image/png'))
{
  // bad
}

Answer 4

You should define a list of accepted mimetypes :

$accepted_types = array(
    'image/gif',
    'image/jpeg',
    'image/png',
);

$uploadfile_type=$_FILES['userfile']['type'];

if (!in_array($uploadfile_type, $accepted_types))
{
    echo 'Problem: file is not a gif or jpeg or png!';
    exit;
}

I hope this will help, Jerome Wagner

Answer 5

There's a riddle that goes:

I have two coins in my pocket. Their total value is thirty cents. One of them is not a nickel. What are they?

The answer is that they are a quarter and a nickel - the quarter satisfies the condition that "one of them is not a nickel". This is the kind of problem you are facing. Every file is not a gif or is not a jpeg - even the gifs and jpegs. The gifs are not jpegs, and the jpegs are not gifs. So, as others have said, you need to use AND instead of OR.