Difference between & and && in PHP

2018-05-29 12:50:53

I am confused with & and && . I have two PHP books. One says that they are same, but the another says they are different. I thought they are same as well.

Aren't they same?

& is bitwise AND. See Bitwise Operators. Assuming you do 14 & 7 :

    14 = 1110
     7 = 0111
    ---------
14 & 7 = 0110 = 6

&& is logical AND. See Logical Operators. Consider this truth table:

 $a     $b     $a && $b
false  false    false
false  true     false
true   false    false
true   true     true

The other answers are correct, but incomplete. A key feature of logical AND is that it short-circuits, meaning the second operand is only evaluated if necessary. The PHP manual gives the following example to illustrate:

$a = (false && foo());

foo will never be called, since the result is known after evaluating false. On the other hand with

$a = (false & foo());

foo will be called (also, the result is 0 rather than false).

 

AND operation: 

& -> will do the bitwise AND operation , it just doing operation based on
      the bit values. 
&&   -> It will do logical AND operation. It is just the check the values is 
       true or false. Based on the boolean value , it will evaluation the 
       expression

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