The function name is: print The function argument or parameter is: "Hello" Let's now feed a variable into print: In this example, print gets the variable outputtextas argument. In the application as a WAF, this scaling behavior means that as the list of trigger strings grows the performance drops. For a MetaLua implementation, see "String Interpolation" in MetaLuaRecipes. -- Interpolates variables into string . 16 bit encoding is used. [abc] meaning the letter a, b, or c). Moreover, as the size of the search space increases, the time to process the data starts to scale significantly. Honestly, there’s not a whole lot to say about this. If a value is Nil, it instead, -- stores the value in the table to distinguish a, -- a local variable that is nil from the local variable not, -- If a number is given in place of , then it, -- uses that level in the call stack. std::string s("123"); int i; std::from_chars(s.data(), s.data() + s.size(), i, 10); Finally I concatenate a search word to either the front or the rear of the random character string to match against. “J” enables the PCRE JIT compilation engine. If an instance of the pattern is found a pair of values representing the start and end of the string is returned. giving lower case characters a higher priority than all of the upper case characters? Lua applies such coercions not only in arithmetic operators, but also in other places that expect a number. Conversely, whenever it finds a number where it expects a string, Lua converts the number to a string: print(10 .. 20) --> 1020 (The .. is the string concatenation operator in Lua. This means that the dictionary size is 65280. The essay "WP:Lua string functions" was created by long-term user Wikid77 to describe the capabilities, performance, and limitations when using Lua script to handle text strings in Wikipedia pages. The early takeaway is to always use string.find() when you can exactly match the string you’re searching for. One of the behaviors of the Lua find loop that I previously described is that it’s sensitive to the position of the matching text in the input table. Compare(String, String, Boolean) Compares two specified String objects, ignoring or honoring their case, and returns an integer that indicates their relative position in the sort order.. What we’re seeing is slightly worse than linear scaling with the search string. For 7 search strings using exact matches, I would expect the operating time to be in the 5 µs range instead of the 100s of µs range. Once you start throwing wildcards into the mix, string.find() slows down considerably. They explode like you would expect, from an O(n) algorithm backed by a relatively slow string processing library. The Lua way is to put the strings into a table and then use table.concat. debug.getlocal() is also expensive since it needs to scan through the entire byte code to figure out which variables are in scope. Am I missing something? While straight exact matches are very fast in Lua’s string.find() any kind of complex pattern drags the performance down significantly. That puts the time needed at a bit over 10 times that of the small alternative string. So each 8 bit character is encoded as 16 bit. While much of the search capabilities looks somewhat like regex in spirit and format, there are significant deficiencies in the string.find() engine that separate it from regex. That said, there are a couple of points worth touching on. Important Note: Somehow, I needed another character as a means to represent the closing brace inside the code, and I have arbitarily chosen '¶' , what this means if somehow you have that character in your string (specially when you are using foreign language encoding) you will get a syntax error. The idea is simple: By giving a device (real or dummy) in Domoticz a name constructed by adding a pre-determined prefix to an existing device/group name, Lua is used to detect when *any* device with that prefix changes state and to carry out a specific action on an existing physical device/group defined already in Domoticz (and named with… The full details are outlined in the above linked Lua5.1 docs page. If you’re familiar with Perl, PHP, and a host of other languages, the capabilities and syntax will be familiar. Upper and Lower Case To convert a string to upper case, use string.upper(str). Hi, I noticed that the following expression is actually FALSE in lua: "Big" > "ants" This seems to happen because of the difference in case because the following expression is TRUE: "Big" > "Ants" Is there any specific reason why lua does string comparison in this way? Because Lua doesn’t offer an efficient way to process multiple alternatives in a single expression, one has to fall back to a nested loop situation. To compare, say, a string and an integer, one would need to call an explicit type conversion for one of these objects. Lua’s native string.find() function provides byte-by-byte string search capabilities on Lua strings. Third, for complex text searches in Lua-Nginx, it’s clearly preferable to use the ngx.re.find functions, not native lua find calls as one might expect. Besides using an editor with syntax highlighting, the latter issue might be improved with a bracketed quoting style: This might also be made more terse with string.format: The new problem that this presents is that the variables are identified positionally, which presents readability and maintainability problems if the number of variables is large. Nginx implements a Perl Compatible Regular Express (PCRE) regex engine. Second, Lua’s native string.find() is extremely fast, so long as it’s being used with exact matches (case sensitive, no globing, no wildcards). -- "nil" value that can be stored in tables. For these tests I generate a random string that’s at least a specified size in bytes (e.g. 本文实现了Lua 中 number 转换各种进制，以及各种进制 string 串转 number。实现思路： 1. Lua and Nginx both offer some options for searching strings. -- obtain local variable from (1 if omitted). 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