Logical Operators, || or OR?
I remember reading a while back in regards to logical operators that in the case of OR, using || was better than or (or vice versa).
I just had to use this in my project when it came back to me, but I can't remember which operator was recommended or if it was even true.
Which is better and why?
There is no "better" but the more common one is ||. They have different precedence and || would work like one would expect normally.
See also: Logical operators (the following example is taken from there):
// 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)
$f = false or true;
They are used for different purposes and in fact have different operator precedences. The && and || operators are intended for Boolean conditions, whereas and and or are intended for control flow.
For example, the following is a Boolean condition:
if ($foo == $bar && $baz != $quxx) {
This differs from control flow:
doSomething() or die();
The difference between respectively || and OR and && and AND is operator precedence :
$bool = FALSE || TRUE;
- interpreted as
($bool = (FALSE || TRUE)) - value of
$boolisTRUE
$bool = FALSE OR TRUE;
- interpreted as
(($bool = FALSE) OR TRUE) - value of
$boolisFALSE
$bool = TRUE && FALSE;
- interpreted as
($bool = (TRUE && FALSE)) - value of
$boolisFALSE
$bool = TRUE AND FALSE;
- interpreted as
(($bool = TRUE) AND FALSE) - value of
$boolisTRUE
Source: http://wallstreetdeveloper.com/php-logical-operators/
Here is sample code for working with logical operators:
<html>
<head>
<title>Logical</title>
</head>
<body>
<?php
$a = 10;
$b = 20;
if ($a>$b)
{
echo " A is Greater";
}
elseif ($a<$b)
{
echo " A is lesser";
}
else
{
echo "A and B are equal";
}
?>
<?php
$c = 30;
$d = 40;
//if (($a<$c) AND ($b<$d))
if (($a<$c) && ($b<$d))
{
echo "A and B are larger";
}
if (isset($d))
$d = 100;
echo $d;
unset($d);
?>
<?php
$var1 = 2;
switch($var1)
{
case 1: echo "var1 is 1";
break;
case 2: echo "var1 is 2";
break;
case 3: echo "var1 is 3";
break;
default: echo "var1 is unknown";
}
?>
</body>
</html>