[RESOLVED] use of OR within ternary/conditional

scrupul0us

is this not valid / possible:

return $string == 'http' | 'www' ? 'URL' : 'file';

johanafm

valid and possible, although I doubt it does what you want it to.

First off, operator precedence.
1. ==
2. |
3 ?:

Thus equivalent to,

( ($string == 'http') | 'www') ? 'URL' : 'file'

So, to evaluate the expression, start with ==

$string == 'http'
	possible values: true, false

If it's true:
true | 'www' ? 'URL' : 'file'

If it's false:
false | 'www' ? 'URL' : 'file'

Next up is |

true | 'www'
	1

false | 'www'

So, evaluating | yields the same as we got from ==, which means we can just remove that part from the original expression. Thus

($string == 'http') ? 'URL' : 'file';

But even if you started with this I doubt you'd get what you want

($string == ('http' | 'www')) ? 'URL' : 'file';

// which is equal to
($string == 'hwww') ? 'URL : 'file);

What you can do

($string == 'http') ? 'URL' : (($string == 'www')  ? 'URL' : 'file');

But I'd much prefer

$url = array('http', 'www');

isset($url[$string]) ? 'URL' : 'file';

scrupul0us

good explanation...

your final is marginally better than what i ended up with:

$substr = strtolower(substr($value,0,4));
return in_array($substr,array('http','www.')) ? 'URL' : 'file';

any difference in performance you think or is it a case of 6-and-a-half-dozen-the-other ?

johanafm

Using array keys means one access to get the result. I don't know what search algorithm is used for in_array, and I don't remember what best performance can be on unsorted arrays, but at worst in_array would need to access half the elements on average. If you have no more than two elements, there is little difference.

Weedpacket

johanafm wrote:
I don't remember what best performance can be on unsorted arrays

Linear; looking at one element doesn't give you any information about any others so you potentially have to look at all of them, but you don't have to look at each element any more than once.