'AND' vs '&&' as operator

Question

I have a codebase where developers decided to use AND and OR instead of && and ||.

I know that there is a

Answer 1

Depending on how it's being used, it might be necessary and even handy. http://php.net/manual/en/language.operators.logical.php

// "||" has a greater precedence than "or"

// The result of the expression (false || true) is assigned to $e
// Acts like: ($e = (false || true))
$e = false || true;

// The constant false is assigned to $f and then true is ignored
// Acts like: (($f = false) or true)
$f = false or true;

But in most cases it seems like more of a developer taste thing, like every occurrence of this that I've seen in CodeIgniter framework like @Sarfraz has mentioned.

Answer 2

Here's a little counter example:

$a = true;
$b = true;
$c = $a & $b;
var_dump(true === $c);

output:

bool(false)

I'd say this kind of typo is far more likely to cause insidious problems (in much the same way as = vs ==) and is far less likely to be noticed than adn/ro typos which will flag as syntax errors. I also find and/or is much easier to read. FWIW, most PHP frameworks that express a preference (most don't) specify and/or. I've also never run into a real, non-contrived case where it would have mattered.

Answer 3

Let me explain the difference between “and” - “&&” - "&".

"&&" and "and" both are logical AND operations and they do the same thing, but the operator precedence is different.

The precedence (priority) of an operator specifies how "tightly" it binds two expressions together. For example, in the expression 1 + 5 * 3, the answer is 16 and not 18 because the multiplication ("*") operator has a higher precedence than the addition ("+") operator.

Mixing them together in single operation, could give you unexpected results in some cases I recommend always using &&, but that's your choice.

---

On the other hand "&" is a bitwise AND operation. It's used for the evaluation and manipulation of specific bits within the integer value.

Example if you do (14 & 7) the result would be 6.

7   = 0111
14  = 1110
------------
    = 0110 == 6

Answer 4

I guess it's a matter of taste, although (mistakenly) mixing them up might cause some undesired behaviors:

true && false || false; // returns false

true and false || false; // returns true

Hence, using && and || is safer for they have the highest precedence. In what regards to readability, I'd say these operators are universal enough.

UPDATE: About the comments saying that both operations return false ... well, in fact the code above does not return anything, I'm sorry for the ambiguity. To clarify: the behavior in the second case depends on how the result of the operation is used. Observe how the precedence of operators comes into play here:

var_dump(true and false || false); // bool(false)

$a = true and false || false; var_dump($a); // bool(true)

The reason why $a === true is because the assignment operator has precedence over any logical operator, as already very well explained in other answers.