the general case of iterating over an array and removing random items from the middle while continuing to iterate If you’re iterating front-to-back, when you remove element N, the next element in your iteration (N+1) gets shifted down into that position. If you increment your iteration variable (as ipairs does), you’ll skip that element. There … Read more
You seem to misunderstand something. What you have here is a associative array. Associative arrays have no explicit order on them, e.g. it’s only the internal representation (usually sorted) that orders them. In short — in Lua, both of the arrays you posted are the same. What you would want instead, is such a representation: … Read more
You already have the solution in the question — the only way is to iterate the whole table with pairs(..). function tablelength(T) local count = 0 for _ in pairs(T) do count = count + 1 end return count end Also, notice that the “#” operator’s definition is a bit more complicated than that. Let … Read more
About tables in general (oh, can’t you just give me an array) In Lua, a table is the single general-purpose data structure. Table keys can be of any type, like number, string, boolean. Only nil keys aren’t allowed. Whether tables can or can’t contain nil values is a surprisingly difficult question which I tried to … Read more
You could use something like a set from Programming in Lua: function Set (list) local set = {} for _, l in ipairs(list) do set[l] = true end return set end Then you could put your list in the Set and test for membership: local items = Set { “apple”, “orange”, “pear”, “banana” } if … Read more
Table copy has many potential definitions. It depends on whether you want simple or deep copy, whether you want to copy, share or ignore metatables, etc. There is no single implementation that could satisfy everybody. One approach is to simply create a new table and duplicate all key/value pairs: function table.shallow_copy(t) local t2 = {} … Read more
Here is my really simple solution. Use the gmatch function to capture strings which contain at least one character of anything other than the desired separator. The separator is **any* whitespace (%s in Lua) by default: function mysplit (inputstr, sep) if sep == nil then sep = “%s” end local t={} for str in string.gmatch(inputstr, … Read more
The error has been documented on the Mac Developer Library(iOS docs) The concerned segment from the documentation will be: URL Loading System Error Codes These values are returned as the error code property of an NSError object with the domain “NSURLErrorDomain”. enum { NSURLErrorUnknown = -1, NSURLErrorCancelled = -999, NSURLErrorBadURL = -1000, NSURLErrorTimedOut = -1001, … Read more
First, compute the center point. Then sort the points using whatever sorting algorithm you like, but use special comparison routine to determine whether one point is less than the other. You can check whether one point (a) is to the left or to the right of the other (b) in relation to the center by … Read more
The colon is for implementing methods that pass self as the first parameter. So x:bar(3,4)should be the same as x.bar(x,3,4).