nok1a Posted April 3, 2023 Share Posted April 3, 2023 How can i start the array with index 0? Link to comment Share on other sites More sharing options...
0 XEKEX Posted April 3, 2023 Share Posted April 3, 2023 (edited) in lua the array always start at index 1 , however you can force it to start with 0 like : table[0] = somthing or table = {} for i = 0 , 10 do table[i] = somthing end or using metamethods note : forcing it to start with index 0 isn't a good practice. Edited April 3, 2023 by XEKEX wrong solution Link to comment Share on other sites More sharing options...
0 CmP Posted April 3, 2023 Share Posted April 3, 2023 Note that metatable-based solution suggested above doesn't work as expected in all cases when key used in indexing access or indexing assignment exists in table, because "__index" and "__newindex" events are used only when key is not present in table. Though, XEKEX is right that it's not a good practice to have 0-based arrays in Lua. What is your use case for that and why 1-based arrays don't suffice? Link to comment Share on other sites More sharing options...
0 XEKEX Posted April 3, 2023 Share Posted April 3, 2023 18 minutes ago, CmP said: Note that metatable-based solution suggested above doesn't work as expected in all cases when key used in indexing access or indexing assignment exists in table, because "__index" and "__newindex" events are used only when key is not present in table. Though, XEKEX is right that it's not a good practice to have 0-based arrays in Lua. What is your use case for that and why 1-based arrays don't suffice? youre right forget that metatable doesn't work with numbers index Link to comment Share on other sites More sharing options...
0 nok1a Posted April 3, 2023 Author Share Posted April 3, 2023 (edited) 1 hour ago, XEKEX said: in lua the array always start at index 1 , however you can force it to start with 0 like : table[0] = somthing or table = {} for i = 0 , 10 do table[i] = somthing end or using metamethods note : forcing it to start with index 0 isn't a good practice. It doesn't start with 0 though. Which is rather the result i want to achieve. Must be chronological order. Edited April 3, 2023 by nok1a added screenshot Link to comment Share on other sites More sharing options...
0 nok1a Posted April 3, 2023 Author Share Posted April 3, 2023 (edited) 1 hour ago, CmP said: What is your use case for that and why 1-based arrays don't suffice? It's for readability. In the game first offset contains no data(strings), i refer by it as sequence 0. Offset is 0 and size is 0 as well. Data only starts at the second offset. Which is actually sequence 1. From there at index 0 i want the sequence 0 which contains no data, then at index 1 i want sequence 1 which contains data. As you can see here, the empty string i not want at index 1. When at index 0 it will be more suitable for me when working with the game data. But i don't try to make it a habit. It's just this type of cases. Edited April 3, 2023 by nok1a added more info Link to comment Share on other sites More sharing options...
0 CmP Posted April 3, 2023 Share Posted April 3, 2023 16 minutes ago, nok1a said: It's for readability. For readability of the code or the output with table representation? If for the latter, one can simply create custom function to print table contents. 35 minutes ago, nok1a said: It doesn't start with 0 though. Which is rather the result i want to achieve. Must be chronological order. There are no regular arrays in Lua, only tables that are associative arrays and can be used to implement many different data structures. Tables in Lua don't have starting element by themselves, but length operator and functions from "table" library operate only on part of table with consecutive integer keys starting from 1. Your interpretation is wrong, because tables don't have defined order of traversal, it's implementation-specific. In fact official Lua doesn't include table contents in it's default procedure to convert table to string. So instead of relying on default table to string conversion in GG implementation of Lua, implement custom function that will perform conversion the way you need. Link to comment Share on other sites More sharing options...
0 nok1a Posted April 11, 2023 Author Share Posted April 11, 2023 (edited) On 4/3/2023 at 10:50 PM, CmP said: For readability of the code or the output with table representation? If for the latter, one can simply create custom function to print table contents. It is only for output table representation. Could you perhaps provide an example function for print table starting at index zero*? It's only for this particular case because in-game indexing starts at 0. On 4/3/2023 at 10:50 PM, CmP said: So instead of relying on default table to string conversion in GG implementation of Lua, implement custom function that will perform conversion the way you need. Thanks lots for the explanation. I had no knowledge of anything you mentioned. Edited April 11, 2023 by nok1a Link to comment Share on other sites More sharing options...
0 CmP Posted April 11, 2023 Share Posted April 11, 2023 17 minutes ago, nok1a said: Could you perhaps provide an example function for print table starting at index zero*? It's not more complicated than to print table elements starting from key 1. Looks more like the question is about how to print table elements at all. In the most basic case to print elements with integer keys starting from 0 and without printing contents of any nested tables it's enough to have one loop: local t = {[0] = 0, 1, 2, 3} print("{") local index = 0 local element = nil while true do element = t[index] if element == nil then break end local representation = string.format(" [%d] = %s", index, element) -- implement custom type-dependent converion of value to string if needed, this one uses default conversion, i.e. string "1" and number 1 will result in the same output print(representation) index = index + 1 end print("}") 1 Link to comment Share on other sites More sharing options...
0 CmP Posted April 11, 2023 Share Posted April 11, 2023 Lua also allows to implement custom iterators to be used with generic "for", so one can implement traversal from 0 that way and use it like ipairs/pairs functions: -- Modified function from http://lua-users.org/wiki/IteratorsTutorial function ipairs0(t) local function iterator(t, i) i = i + 1 local v = t[i] if v ~= nil then return i, v else return nil end end return iterator, t, -1 end -- Usage example for i, v in ipairs0(t) do print(string.format("[%d] = %s", i, v)) end Link to comment Share on other sites More sharing options...
0 XEKEX Posted April 12, 2023 Share Posted April 12, 2023 On 4/3/2023 at 8:48 PM, nok1a said: It doesn't start with 0 though. Which is rather the result i want to achieve. Must be chronological order. this is why it's not a good practice because ipairs , pairs and every built-in functions in lua that deals with tables start the iteration by default at index 1 --> here is an example Link to comment Share on other sites More sharing options...
0 nok1a Posted April 12, 2023 Author Share Posted April 12, 2023 5 hours ago, XEKEX said: this is why it's not a good practice because ipairs , pairs and every built-in functions in lua that deals with tables start the iteration by default at index 1 --> here is an example It is only for table readability when using print. If indexing in the game starts at zero then i do want the index of the table,(for readability when using print) to start at zero. Not that it firsts shows index 1 and then all at the end shows index 0. It's a simple thing for the sake of not getting any confusion. I would not do it if i needed to use the table for something else. Link to comment Share on other sites More sharing options...
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How can i start the array with index 0?
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