why does this always die ?

Question

$extension = "jpg"

    if($extension != "jpg" || $extension != "gif" || $extension != "png") die("only jpg, gif, png acceptable");

it always seems to die().

Answer 1

You want && not ||.

Read it outloud as:

"If x doesn't equal Y OR x doesn't equal N".

Clearly, it doesn't matter what x equals, as long as Y and N aren't equal, the statement will always be true :)

Answer 2

Since $extension cannot be "jpg", "gif" and "png" at the same time, at least two of the sub-conditions are true.

And, since you're using or (||) instead of and (&&), any true sub-condition will render the entire condition true.

You want something like:

if (($extension != "jpg") && ($extension != "gif") && ($extension != "png")) {
    die ("only jpg, gif, png acceptable");
}

Answer 3

$extension = "jpg"

    if($extension != "jpg" && $extension != "gif" && $extension != "png") die("only jpg, gif, png acceptable");

This may work

Answer 4

You are using the NOT EQUAL TO operator with a bunch of ORs.

$extension = "jpg"
if ($extension != "jpg" || 
    $extension != "gif" || 
    $extension != "png") 
    die("only jpg, gif, png acceptable");

You could fix this one of two ways:

• Switch all || to &&
• Simplify it be having an array of valid extensions:

---

$valid = array('jpg' => true, 'gif' => true, 'png' => true);
if (!isset($valid[$extension])) {
    // not a valid extension
}

Answer 5

Reasons are already explained, moreover you can simply do this, with the result you expected:

$extension = "jpg";
if(!in_array($extension,array("jpg","gif","png"))){
    die("only jpg, gif, png acceptable");
}