CODEWITHSUNDEEP
phpoperatorsporting
Kenny Winker
Kenny Winker

Reputation: 12107

In php what does the 'double greater than' symbol mean?

I have this code, I'm trying to port from php to c/objective-c:

if ($byteIndex < count($data) ) {
    $light = ( ( ($data[$byteIndex] >> $bitIndex) & 1) == 1);
}

But I can't seem to find anywhere what the >> is indicating here. nor the "& 1", for that matter.

Upvotes: 2

Views: 4950

Answers (1)

Dejan Marjanović
Dejan Marjanović

Reputation: 19380

Bitwise operators - Shift Right and And :)

http://php.net/manual/en/language.operators.bitwise.php

http://en.wikipedia.org/wiki/Bitwise_operation

$score = 2295;

echo((($score >> 2) & 1) == 1)? "1": "^1"; // 1
echo((($score >> 3) & 1) == 1)? "1": "^1"; // ^1

The question is what are you shifting and how many bits? Is it something with colors?

Using & and >> to convert hexadecimal to RGB (decimal).

$hex = 0xCCFF33; // my favourite :)

$r = $hex >> 16;
$g = ($hex & 0x00FF00) >> 8;
$b = $hex & 0x0000FF;

printf("rgb(%d,%d,%d)", $r, $g, $b); // rgb(204,255,51)

This is what happens: http://publib.boulder.ibm.com/infocenter/comphelp/v8v101/index.jsp?topic=%2Fcom.ibm.xlcpp8a.doc%2Flanguage%2Fref%2Fbitshe.htm

Upvotes: 8

Related Questions