php: is valid to use if/else in this way?

Question

Is there a way to optimize something like this?
I have already tried and it doesn't work (at least in php)

$foo = 6;
if ($foo != (3 or 5 or 10)) echo "it work";
elseif($foo < (5 or 10)) echo "it work again";
else echo "it doesn't work;"

I want to know if there's a better way to write that kind of validations.
But if something like this work in other langs, please let me know.

EDIT:
answer for this

($foo != (3 or 5 or 10)) -> in_array($foo,array(3,5,10))

does the same work if i want something like

($foo != (3 and 5 and 10))

Marc B · Accepted Answer · 2014-04-14 19:38:13Z

3

No. It's not. You're testing your $foo value against the BOOLEAN result of those or operations. It'll boil down to

if ($foo != (true or true or true))

which is simply

if ($foo != true)
if (!$foo)

If you want to test a single value against multiple values, you can try

if(!in_array($foo, array(3,5,10))) { ... }

instead. For your < version, this won't work. You'll have to test each value individually:

if (($foo < 5) or ($foo < 10)) { ... }

though technically this is somewhat redundant, since if $foo is less than 5, it's already less than 10.

answered Apr 14, 2014 at 19:38

Marc B

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1 Comment

MonkeyZeus Over a year ago

+1 This is an excellent answer but I think the real issue that needs to be addressed is the fact that micro-optimization is 99% not worth the effort and makes code illegible for future reading.

Fuzzyma · Accepted Answer · 2014-04-14 19:40:31Z

0

For the first you can use

if(!in_array($foo, [5,10,15]))

The second thing doesn't work in any language cause less then 5 or 10 is true for every thing less than 10. So no need for the 5. But I get your point. I don't know a fast way doing this

In python you can do this:

if(5 < x < 10)
    a, b = b, a // swapping these two

answered Apr 14, 2014 at 19:40

Fuzzyma

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Comments

Florin Asăvoaie · Accepted Answer · 2014-04-14 19:47:57Z

0

I agree with the other answers and also, if you have more processing to do, you could also do something like this:

<?php

$x = 3;

switch ($x)
{
    case 6:
        $x = 5;
    case 3:
    case 7:
        $x = 5;
    case 5:
        echo 'It is working' . PHP_EOL;
        break;
}

EDIT: Thanks DanFromGermany for pointing the stacked cases. Added them as an example.

edited Apr 14, 2014 at 19:47

answered Apr 14, 2014 at 19:42

Florin Asăvoaie

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5 Comments

MonkeyZeus Over a year ago

You forgot the break;s

Florin Asăvoaie Over a year ago

No, I did not. Why would you exit the loop before doing your job?

Fuzzyma Over a year ago

No need for breaks if you don't want them!

Daniel W. Over a year ago

or stack the cases: case 6: case 3: $x = 5;

thetaiko Over a year ago

@FlorinAsavoaie - without the break; the first and second cases will both run if $x == 6. In this case, it doesn't matter because they do the same thing, but can be a dangerous mistake.

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