PHP Logical Operators

In PHP, logical operators are used to combine conditional statements.

Here are the logical operators available in PHP:

And (&&): This operator returns true if both conditions are true.
Or (||): This operator returns true if either (or both) of the conditions are true.
Not (!): This operator returns true if the condition is not true (i.e., it reverses the condition).
Xor: This operator returns true if exactly one of the conditions is true, but not both.

Here's an example of how to use each one:

$x = 10;
$y = 20;

// And Operator
if ($x == 10 && $y == 20) {
    echo "True"; // This will output "True" because both conditions are true.
} else {
    echo "False";
}

// Or Operator
if ($x == 10 || $y == 30) {
    echo "True"; // This will output "True" because one of the conditions is true.
} else {
    echo "False";
}

// Not Operator
if (!($x == 20)) {
    echo "True"; // This will output "True" because $x is not equal to 20.
} else {
    echo "False";
}

// Xor Operator
if ($x == 10 xor $y == 30) {
    echo "True"; // This will output "True" because only one of the conditions is true.
} else {
    echo "False";
}

These operators are very useful for controlling the flow of your program based on multiple conditions. Use parentheses to make complex conditions more clear and to control the order in which the conditions are evaluated.

Using AND, OR, and NOT in PHP:

$a = true;
$b = false;

// AND operator
$result_and = $a && $b; // false

// OR operator
$result_or = $a || $b;  // true

// NOT operator
$result_not = !$a;      // false

Combining logical operators in PHP expressions:

$x = 5;
$y = 10;

// Combined expression
$result_combined = ($x > 0 && $y < 15) || ($y == 10); // true

Order of precedence with PHP logical operators:

$a = true;
$b = false;
$c = true;

// Precedence: AND > OR
$result_precedence = $a || $b && $c; // true

Short-circuit evaluation in PHP:

$a = true;
$b = false;

// Short-circuit AND
$result_short_and = $a && ($b = true); // $b remains false

// Short-circuit OR
$result_short_or = $a || ($b = true);  // $b becomes true

Boolean values and comparisons in logical expressions:

$num = 10;

// Comparison in logical expression
$result_comparison = ($num > 5) && ($num < 15); // true

Complex conditions with parentheses in PHP:

$x = 8;
$y = 20;

// Complex condition
$result_complex = ($x > 5 && $y < 15) || ($y == 20); // true

Bitwise logical operators in PHP:

$a = 5; // binary: 0101
$b = 3; // binary: 0011

// Bitwise AND
$result_bitwise_and = $a & $b; // 1 (binary: 0001)

// Bitwise OR
$result_bitwise_or = $a | $b;  // 7 (binary: 0111)

Examples of practical usage of PHP logical operators:

Checking user permissions:

$is_admin = true;
$can_edit = true;
$can_delete = false;

$can_manage = ($is_admin && ($can_edit || $can_delete));

Form validation:

$username = "user123";
$password = "pass123";

$is_valid = (strlen($username) >= 6 && strlen($password) >= 8);

Filtering data:

$price = 25;
$quantity = 3;

$is_discounted = ($price > 20 && $quantity >= 3);