{"id":427,"date":"2009-10-12T08:12:20","date_gmt":"2009-10-12T15:12:20","guid":{"rendered":"https:\/\/actionsnippet.com\/?p=2309"},"modified":"2009-10-12T08:12:20","modified_gmt":"2009-10-12T15:12:20","slug":"bitwise-or-and-variable-function-arguments","status":"publish","type":"post","link":"https:\/\/actionsnippet.com\/?p=427","title":{"rendered":"Bitwise OR | and Variable Function Arguments (bitwise flags)"},"content":{"rendered":"
\r\nconst A:uint = 1;\r\nconst B:uint = 2;\r\nconst C:uint = 4;\r\nconst D:uint = 8;\r\nconst E:uint = 16;\r\n\r\nfunction orArgs(args:uint):void{\r\n\tif (args & A){\r\n\t\ttrace("A");\r\n\t}\r\n\tif (args & B){\r\n\t\ttrace("B");\r\n\t}\r\n\tif (args & C){\r\n\t\ttrace("C");\r\n\t}\r\n\tif (args & D){\r\n\t\ttrace("D");\r\n\t}\r\n\tif (args & E){\r\n\t\ttrace("E");\r\n\t}\r\n}\r\n\r\n\/\/ test out the function: \r\norArgs(A | B);\r\ntrace("--");\r\norArgs(A | C | E);\r\ntrace("--");\r\norArgs(B | E | D);\r\ntrace("--");\r\norArgs(C | A);\r\n\r\n\/* outputs: \r\nA\r\nB\r\n--\r\nA\r\nC\r\nE\r\n--\r\nB\r\nD\r\nE\r\n--\r\nA\r\nC\r\n*\/\r\n<\/pre>\n
If you’ve every used Array.sort(Array.NUMERIC | Array.DESCENDING) you should have at least a vague idea about what this snippet is doing. It shows how you can pass a variable number of arguments to a function using | (bitwise OR) and & (bitwise AND). I believe the correct term for these kind of arguments is “bitwise flags”. This snippet works by having a series of constant values… in this case A – E. Each constant is assigned an unsigned integer… now you may not see the significance of the values 1, 2, 4, 8 and 16 until you see them in binary… get ready this is a pretty cryptic description…<\/p>\n
A = 00001 = 1
\nB = 00010 = 2
\nC = 00100 = 4
\nD = 01000 = 8
\nE = 10000 = 16<\/p>\n
If we OR all these together we get: 11111… If we do:<\/p>\n
 A | E
\n00001 | 10000 <\/p>\n
we end up with 10001…<\/p>\n
…we can then check which values are stored in the resulting unsigned integer by using AND:<\/p>\n
check for A… 10001 & 00001 = 00001 = true
\ncheck for E… 10001 & 10000 = 10000 = true
\ncheck for C… 10001 & 00100 = 00000 = false<\/p>\n
That’s it… I just guessed at the way this was being done… if you have another way to do the same thing, feel free to post it in the comments….<\/p>\n","protected":false},"excerpt":{"rendered":"
const A:uint = 1; const B:uint = 2; const C:uint = 4; const D:uint = 8; const E:uint = 16; function orArgs(args:uint):void{ if (args & A){ trace("A"); } if (args & B){ trace("B"); } if (args & C){ trace("C"); } if (args & D){ trace("D"); } if (args & E){ trace("E"); } } \/\/ test […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[137,121,94,36],"tags":[3,14,38,4],"class_list":["post-427","post","type-post","status-publish","format-standard","hentry","category-binary","category-math","category-misc","category-operators","tag-actionscript","tag-as3","tag-binary","tag-flash"],"_links":{"self":[{"href":"https:\/\/actionsnippet.com\/index.php?rest_route=\/wp\/v2\/posts\/427","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/actionsnippet.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/actionsnippet.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/actionsnippet.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/actionsnippet.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=427"}],"version-history":[{"count":0,"href":"https:\/\/actionsnippet.com\/index.php?rest_route=\/wp\/v2\/posts\/427\/revisions"}],"wp:attachment":[{"href":"https:\/\/actionsnippet.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=427"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/actionsnippet.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=427"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/actionsnippet.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=427"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}