for array_filter, I considered an example from php official site. I found a example there
function odd($var)
{
// returns whether the input integer is odd
return($var & 1);
}
function even($var)
{
// returns whether the input integer is even
return(!($var & 1));
}
both function return return($var & 1) and return(!($var & 1)); I can not understand properly what does it mean and specially why 1 is there in return
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2possible duplicate of Understanding PHP & (ampersand, bitwise and) operatorfedorqui– fedorqui2015年01月15日 10:49:56 +00:00Commented Jan 15, 2015 at 10:49
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Actually the returns are different. I suggest what @fedorqui commented just right before me.Masiorama– Masiorama2015年01月15日 10:50:45 +00:00Commented Jan 15, 2015 at 10:50
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I would suggest reading this topic: stackoverflow.com/questions/3737139/…Forien– Forien2015年01月15日 10:51:59 +00:00Commented Jan 15, 2015 at 10:51
1 Answer 1
It's pretty simple: & is a bitwise AND operator and it works as followed:
A | B
---------------
0 | 0 -> 0
1 | 0 -> 0
0 | 1 -> 0
1 | 1 -> 1
And if you take as an example 2, 3 and 6 for odd then this is what's going on:
0000 0010 -> 2
0000 0001 -> 1
--------- &
0000 0000 = return 0
0000 0011 -> 3
0000 0001 -> 1
--------- &
0000 0001 = return 1
0000 0110 -> 6
0000 0001 -> 1
--------- &
0000 0000 = return 0
So in other words if the first digit (1) is 'on' it's going to return 1 because it's odd and if not it's going to return 0
And the same is going on for even just with a NOT (!) operator
answered Jan 15, 2015 at 10:52
Rizier123
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