PHP

Logical Operators

Logical operators are typically used with Boolean (logical) values; when they are, they return a Boolean value. However, the && and || operators actually return the value of one of the specified operands, so if these operators are used with non-Boolean values, they may return a non-Boolean value.

Operator	Description	Example
&& and	And	$a and $b returns TRUE if both $a and $b are TRUE. && has a higher precedence than and.
\|\| or	Or	$a or $b returns TRUE if either $a or $b is TRUE. \|\| has a higher precedence than or.
!	Not	!$a returns TRUE if $a is not TRUE.
xor	Xor	$a xor $b returns TRUE if either $a or $b is TRUE, bjut not both.

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<title>PHP</title>
<meta Name="Author" Content="Hann So">
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<body>
<p>
<?php
// "&&" has a greater precedence than "and"
$e = true && false; // $e will be assigned to (true && false) which is false
$f = true and false; // $f will be assigned to true
echo "The value of e = true && false is: ", $e, "<br />";
echo "The value of f = true and false is: ", $f, "<br />";

// "||" has a greater precedence than "or"
$g = false || true; // $g will be assigned to (false || true) which is true
$h = false or true; // $h will be assigned to false
echo "The value of g = false || true is: ", $g, "<br />";
echo "The value of h = false or true is: ", $h, "<br />";

$a = 1;
$b = 2;
$c = 5;
echo "a = ", $a,"<br />";
echo "b = ", $b,"<br />";
echo "c = ", $c,"<br />";

echo "The value of !($a > $b && $b < $c) is: ", !($a > $b && $b < $c), "<br />";// true
echo "The value of (($a > $b) and ($b < $c)) is: ", (($a > $b) and ($b < $c)), "<br />";// false
echo "The value of ($a == $b or $b < $c) is: ", ($a == $b or $b < $c), "<br />"; // true
echo "The value of $a == $b || $b < $c is: ", $a == $b || $b < $c, "<br />"; // true

$x = $a < $b; //$x = true
$y = $b === $c; //$y = false
echo "x = $a < $b is: ", $x,"<br />";
echo "y = $b == $c is: ", $y,"<br />";
echo "The value of x xor y is: ", $x xor $y; // true
?>
</p>
</body>
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