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PHP Integer Configuration (e.g. 1=apache,2=php,3=apache+php)

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+3 A:

You don't just have a sum -- you have yourself a set of flags, or a bit field, with each flag represented by one bit.

$logging     = !!($cfgval & 1);
$errorReport = !!($cfgval & 2);
$emailReport = !!($cfgval & 4);

The "!!" just ensures that numbers that aren't 0 (ie: numbers with the specific bit set) end up as the same "true" value that the rest of PHP uses, so stuff like ($logging == true) always works as expected. It's not required, but i highly recommend you convert the value to a boolean somehow; (bool) would work as well, even if it is 3 times as many characters. :)

As long as you keep the numbers as powers of two (1, 2, 4, 8, 16, 32...), it's easy to extend this up to 31-32 different flags (integers are 32 bits in size, but the top bit is a sign bit which acts kinda funny if you don't know about "two's complement" math).

cHao 2010-07-17 23:56:37

@chao, do u think, that one will put a configuration key/value like 1024, 2048, ..., 16384, ... so on? is it handy or feasible? i dont think so.

Sadat 2010-07-18 00:02:21

@Sadat: sure. Define constants for the values, and it's extremely easy to work with. Not so easy for a human to put into a config file, but that's something a decent setup/install page could whip up in no time. Or you could use hex numbers, where 4 bits == 1 digit, and it gets a lot easier even for humans.

cHao 2010-07-18 00:05:40

Why should `!!` be better than `(bool)`?

Mikulas Dite 2010-07-18 00:24:25

It'd work the same, i imagine. `!!` is shorter, though, and makes just as much sense to me.

cHao 2010-07-18 01:26:32

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PHP Integer Configuration (e.g. 1=apache,2=php,3=apache+php)

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