Programming

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Operators / Logical

Logical

All logical operators only work with Boolean values. 
 
/**
 * AND &&   True if BOTH operands evaluate to true
 * OR ||    Evaluates to true if EITHER operands true
 * XOR      Evaluates to true if either operands true, but NOT BOTH
 * 
 * PHP will first convert any other value to a Boolean ...
 * and then perform the operation
 */

$a = 1; $a2 = null; $a3 = 'NULL';

var_dump(isset($a) && isset($a2)); // false
var_dump(isset($a) && isset($a3)); // true

var_dump(isset($a) || isset($a2)); // true
var_dump(isset($a) || isset($a3)); // true

$a = "1"; $b = "abc";

var_dump(is_numeric($a) XOR is_numeric($b)); // true
var_dump($a && $b); // true, automatic convertion to Boolean

Shorthands

There are a couple less known operators. 
 
/**
 * Ternary
 * 
 * x = expr1 ? expr2 : expr3
 * x = expr2 if expr1 = TRUE
 * 
 * Ternary shorthand
 * 
 * x = expr1 ?: expr3
 * x = expr1 if expr1 = TRUE
 * 
 * Null coalescing
 * 
 * x = expr1 ?? expr2
 * x = expr1 if expr1 exists and not null
 */

$a = 1;
$b = 1;

var_dump($a == $b ? "true" : "false");  // true
var_dump($a ?: $b);                     // 1
var_dump($n ?? "None");                 // None




References


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