PHP != and == operators

This has boggled me for a while. I am running through a directory and echo'ing out its contents, and I want to exclude the ".." and "." files.

Now, this code works:

if ($files = scandir("temp/"))
{
    foreach ($files as $file)
    {
        if ($file == ".." OR $file == ".")
        {
        }
        else {
            echo $file;
            echo "<br>";
        }
    }
}

But this doesn't...

if ($files = scandir("temp/"))
{
    foreach ($files as $file)
    {
        if ($file != ".." OR $file != ".")
        {
            echo $file;
            echo "<br>";
        }
    }
}

For obvious reasons the second lump of code is more what I want, because I really hate having the true statement do nothing.

---

If you negate a condition consisting of two single conditions and a conjunction ("and" or "or"), you need to negate each condition separately and use the other conjunction.

So try this instead:

if ($file != ".." AND $file != ".")

---

This is one of deMorgan's Laws.

not (A OR B) = (not A) AND (not B)

The change you are making is a refactoring called Reverse Conditional

---

They're not opposites...

Check out de Morgan's laws.

if($file != ".." OR $file != ".")

should be

if($file != ".." AND $file != ".")

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