Is this Valid PHP? Complex If statement - php

Question

can I do something like
if($x != (y&&z&&r&&w))
Or do I have to write it like this
if($x!=y && $x!=z && $x!=r && x!=w)
Just wondering because I have lots of variables to compare and just wanted a more elegant solution.
You might have a more elegant solution anyway. Here's what I'm trying to do.
foreach($_POST as $key => $value){
if($key != 'category_id'){
$cp[$key] = $value;
}
}
And I have about 6 more variables to compare in my $_POST statement and I would like to make the code pretty. It's basically a huge form that needs to format into a specific array ($cp[]) with specific keys to use my MySQL insert statement.
Any fancy ideas?

Answer 1

Your first portion of code :
if($x != (y&&z&&r&&w))
will evaluate the constants y, z, r and w (strings 'y', 'z', 'r' and 'w', if those constants don't exist) ; doing a AND between each one of those.
And, then, the result of this AND will be compared to $x -- which will be considered as a boolean.
So, no, it's not quite doing what you hoped for ; you must use your second portion of code :
if($x!=y && $x!=z && $x!=r && x!=w)
Note that here, too, it'll search for constants called y, z, r and w (or strings, if those constants still don't exist) -- you should probably put some $ in front of those, if you expect them to be treated as variables.
If you want to test if a variable has one of several values, a possible solution is to put those values into an array, and, then, use the in_array() function :
if (in_array($x, array(10, 20, 30) )) {
// $x is one of those values : 10, 20, 30
}
Some think it's easier to understand this way than writing several comparisons -- I sometimes use this myself, and kind of like it.

Answer 2

You'll have to write the long form or use in_array and an array containing your values.

Answer 3

You you can not do it like this:
if($x != (y&&z&&r&&w))
They have to be separated out in to 4 comparisons.
Alternatively, what you can do is stick the values in an array and have only 1 comparison:
$skip_keys = array('a', 'b', 'c', 'd');
foreach ($_POST AS $key => $value) {
if ( ! in_array($key, $skip_keys)) {
// Continue
}
}

Answer 4

You can't say
if ($x != (1&&2&&3))
like that
I also was wondering in my early years whether we can do
if (1 < $x < 5)
and the answer is no too. But you can use in_array() to test if something in an array for you to check several values at once:
http://php.net/manual/en/function.in-array.php

Answer 5

My recommendation, if you're doing this comparions multiple times, is to write a function that validates your requirements for it. So you'll pass in your '$x' and can compare that to everything you need, and will get a boolean result. The function can be structured nicely with ifs and elseifs and you'll keep your code cleaner.
So, example...
<?php
// random, bad logic, but you get the idea
function validateThisThing($x) {
$toReturn = false;
if ($x == 'this') {
$toReturn = true;
} elseif ($x == 'that') {
$toReturn = true;
}
return $toReturn;
}
Then you can just use that function as needed and keep your checks cleaner and more structured as your function name will bring context into what's being checked.