RE: [PHP] How do I convert an array into a mask?

Michael, I like your idea, and had I designed this site, I would have the bitmask simmilar to what you suggest. However, I'm a contractor modding an existing/legacy site. Basically the way they have it, is that each user has a field in the db that is simply a string/mask of which books a person has access to see. So given the example below, "10110" means that the person can view books 1, 3, and 4, but not 2 or 5. dig? Now, I can brute force this, since there are only a few books. That doesn't lend itself nicely to expansion, but may be my only way. I just have a gut feeling that it can be automated somehow. To turn 1,3,4 into 10110 seems like there is some 'math' there that can work. I also thought there might be a built in PHP function that may point me in the right direction. I'll post my solution when I get it working if it's elegant... Thanks anyways. P.s. thanks for the correction on boolean vs bitwise OR. Duh. I should have known that ;-) > -----Original Message----- > Does anyone know of a nice efficient way to convert an array > of values into a "mask"... > > Here's the deal. Given an array such that: > > $purchitem[0] = 1; > $purchitem[1] = 3; > $purchitem[2] = 4; > > I want to end up with a variable like this: > > $mask = "10110"; > > Additionally, my theory is that then the person purchases > another book later > > $purchitem[0] = 2; > > My new mask should be $purchmask = "01000"; > > Then I can load their previous mask from the database and > bitwise OR it with the new mask to set the correct permissions. i.e. > > $newmask = $mask | $purchmask; > > Or ideally = "11110" > > Can I boolean OR strings like that in the way I 'hope' it > will work? Do I need to convert it to an intermediate stage > or cast it or anything? > > Does this make sense? It's for an online book shopping cart. > I have the reverse working, where I can split the mask into > what books. And I also have the $purchitem[] working.