If not or statements

Very simple question... I'm having an issue that an if statement isn't working? All I want is the statement to be that if when $quantity is not equal to 20, or 40, or 80, or 160 to display here.

if($quantity != '20' || $quantity !='40' || $quantity != '80' || $quantity != '160')
{       
echo "here";
}

Any suggestions would be ap开发者_Python百科preciated. :)

Try this, it's cleaner (IMO) :

if (!in_array($quantity, array(20, 40, 80, 160))
{
    echo "here";
}

Else just replace || with &&.

replace the || (or) by && (and) ;)

This way you check if something is 20, then you check if something is 40, etc. So when you have for example 40 the first check (!=20) just returns True (since you are using or's) and it never reaches the second or further check.

If $quantity is 40, it is not 20, so the condition is satisfied.

Study and understand http://en.wikipedia.org/wiki/De_Morgan%27s_Law .

If you don't want $quantity to be equal to any of them, you need to change your '||' or operator to the and operator '&&'.

I made it easier to check for higher numbers, by figuring out your algorithm.

Iterative:

<?php
for ($i = 0; $i <= 3; $i++) {
  if ($quantity == pow(2,$i)*20) { echo "not here"; goto matched; }
}
echo "here";
matched:
?>

More functional:

<?php
if (!in_array($quantity,
  array_map(
    function ($i) { return pow(2,$i)*20; },
    range(0,3)
  )
)) {
  echo "here";
} else {
  echo "not here";
}
?>