Zend Preparation | PHP Quiz (Learning Mode)

PHP Basics Learning Mode

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What is the output from this script?

<?php
$a = true;
$b = false;
$ampBool = $a && $b;
$andBool = $a and $b;
var_dump($ampBool == $andBool);
?>

bool(true)

bool(false)

Comparison between ‘AND’ and ;&&’ operator: There are some difference between both operator are listed below:

Based on Precedence: Precedence basically decides which operations are performed first in an expression. The precedence of ‘&&amp’ operator is high and the precedence of AND operator is low.
Based on operation:

<?php
// Expression to use && operator 
$bool = TRUE && FALSE; 

// Display the result of && operation 
echo ($bool ? 'TRUE' : 'FALSE'), "\n"; 

// Expression to use AND operator 
$bool = TRUE and FALSE; 

// Display the result of AND operation 
echo ($bool ? 'TRUE' : 'FALSE');  
?> 
Output:
FALSE
TRUE

Explanation:
The result of both operator is different whenever operands are same. The first expression evaluates to FALSE while the second expression evaluates TRUE even though both are using the same operation.

The first expression, $bool = TRUE && FALSE; evaluates to FALSE because first && operation is performed, then the result to assigned to the variable $bool because precedence of && operator is higher than the precedence of =. The second expression, $bool = TRUE and FALSE; evaluates to TRUE because the operator and has lower precedence than the operator = so the value TRUE which is on the right of = is assigned to $bool and then the and operation is performed internally but is not assigned, therefore $bool now holds TRUE. So to explain, the fundamental difference in the AND operator and the && operator is their precedence difference but both perform the same operation.