can someone help me with string concatenate problem. I read data from register. It's function utf(regAddr, length). I get table with decimal numbers, then I transform it into hex and to string in loop. I need concatenate these strings into one.
there is not in Lua something like .= operator
function utf(regAddr, length)
stringTable = {}
table.insert(stringTable, {mb:readregisters(regAddr-1,length)})
for key, value in pairs(stringTable) do
for i=1, length do
v = value[i]
v = lmcore.inttohex(v, 4)
v = cnv.hextostr(v)
log(v)
end
end
end
-- function(regAddr, length)
utf(30,20)
There is no append operator for strings. Strings are immutable values.
The .. operator concatenates two string, producing a third string as a result:
local b = "con"
local c = "catenate"
local a = b .. c -- "concatenate"
The table.concat function concatenates strings in a table, producing a string result:
local t = { "con", "catenate" }
local a = table.concat(t) -- "concatenate"
local t = { "two", "words" }
local a = table.concat(t, " ") -- "two words"
The string.format function takes a format pattern with a list of compatible values, producing a string result:
local b = 2
local c = "words"
local a = string.format("%i %s", b, c) -- "2 words"
local t = { 2, "words" }
local a = string.format("%i %s", unpack(t)) -- "2 words"
If you are accumulating a lot of strings that you eventually want to concatenate, you can use a table as a temporary data structure and concatenate when you are done accumulating:
local t = {}
for i = 1, 1000 do
table.insert(t, tostring(i))
end
local a = table.concat(t) -- "1234...9991000"
For a very large number of strings, you can concatenate incrementally. See LTN 9: Creating Strings Piece by Piece and related discussions.
You should try the table.concat method.
Maybe this other question can help you:
Lua table.concat
Checkout this tutorial http://lua-users.org/wiki/TableLibraryTutorial
this code works:
function utf(regAddr, length)
stringTable = {}
table.insert(stringTable, {mb:readregisters(regAddr-1,length)})
for key, value in pairs(stringTable) do
t = {}
for i=1, length do
v = value[i]
v = lmcore.inttohex(v, 4)
v = cnv.hextostr(v)
table.insert(t, v)
end
a = table.concat(t)
end
end
-- function(regAddr, length)
utf(30,20)
Related
I am trying to generate a unique MAC id from given a number value. The length on the number is between 1 to 5 digit. I have formatted the MAC table to place each digit starting from first value of MAC.
local MacFormat ={[1] = "0A:BC:DE:FA:BC:DE",[2] = "00:BC:DE:FA:BC:DE",[3] = "00:0C:DE:FA:BC:DE",[4] = "00:00:DE:FA:BC:DE",[5] = "00:00:0E:FA:BC:DE"}
local idNumbers = {[1] = "1",[2]="12",[3]="123",[4]="1234",[5]="12345"}
for w in string.gfind(idNumbers[3], "(%d)") do
print(w)
str = string.gsub(MacFormat[3],"0",tonumber(w))
end
print(str)
---output 33:3C:DE:FA:BC:DE
--- Desired Output 12:3C:DE:FA:BC:DE
I have tried multiple Patterns with *, +, ., but none is working.
for w in string.gfind(idNumbers[3], "(%d)") do
print(w)
str = string.gsub(MacFormat[3],"0",tonumber(w))
end
print(str)
Your loop body is equivalent to
str = string.gsub("00:0C:DE:FA:BC:DE", "0",1)
str = string.gsub("00:0C:DE:FA:BC:DE", "0", 2)
str = string.gsub("00:0C:DE:FA:BC:DE", "0", 3)
So str is "33:3C:DE:FA:BC:DE"
MacFormat[3] is never altered and the result of gsub is overwritten in each line.
You can build the pattern and replacement dynamically:
local MacFormat ={[1] = "0A:BC:DE:FA:BC:DE",[2] = "00:BC:DE:FA:BC:DE",[3] = "00:0C:DE:FA:BC:DE",[4] = "00:00:DE:FA:BC:DE",[5] = "00:00:0E:FA:BC:DE"}
local idNumbers = {[1] = "1",[2]="12",[3]="123",[4]="1234",[5]="12345"}
local p = "^" .. ("0"):rep(string.len(idNumbers[3])):gsub("(..)", "%1:")
local repl = idNumbers[3]:gsub("(..)", "%1:")
local str = MacFormat[3]:gsub(p, repl)
print(str)
-- => 12:3C:DE:FA:BC:DE
See the online Lua demo.
The pattern is "^" .. ("0"):rep(string.len(idNumbers[3])):gsub("(..)", "%1:"): ^ matches the start of string, then a string of zeros (of the same size a idNumbers, see ("0"):rep(string.len(idNumbers[3]))) follows with a : after each pair of zeros (:gsub("(..)", "%1:")).
The replacement is the idNumbers item with a colon inserted after every second char with idNumbers[3]:gsub("(..)", "%1:").
In this current case, the pattern will be ^00:0 and the replacement will be 12:3.
See the full demo here.
I have this string text:
text = "hotkey=F4,value=,autoSend=false, hotkey=Shift+F9,value=,autoSend=false, hotkey=F5,value=,autoSend=false"
and I would like to convert it to a table like this one:
local table = {
{hotkey='F4', value=nil, autoSend=false};
{hotkey='Shift+F9', value=nil, autoSend=false};
{hotkey='F5', value=nil, autoSend=false}
}
This solution is limited in scope and will not cover all complexities in the input string. A simple pattern matching could generate tables you are looking for, but use this code to build a better/robust regex for the diversity of your strings
s = "hotkey=F4,value=,autoSend=false, hotkey=Shift+F9,value=,autoSend=false, hotkey=F5,value=,autoSend=false"
local words = {}
for w in s:gmatch("(hotkey=%g-,value=%g-,autoSend=%w*)") do
-- Split string in more managebale parts
-- i-g w = 'hotkey=F4,value=,autoSend=false, hotkey=Shift+F9'
-- Extract indivisual k,v pairs and insert into table as desired
local _hotkey = string.match(w,"hotkey=(%g-),")
local _value = string.match(w,"value=(%g-),")
local _autoSend = string.match(w,"autoSend=(%w+)")
table.insert(words,{hotkey=_hotkey, value=_value, autoSend=_autoSend})
end
for _, w in ipairs(words) do
for k, v in pairs(w) do
print(k .. ':' .. v)
end
end
Regex Explanation
(): Capture string
%g: printable characters except for spaces
%w: alphanumeric characters
* : 0 or more repetitions
- : 0 or more lazy repetitions
I have a string x: x = "{abc}{def}{ghi}"
And I need to print the string between second { and second }, in this case def. How can I do this without knowing the length of the string? For example, the string x could also be {abcde}{fghij}{klmno}"
This is where pattern matching is useful:
local x = "{abc}{def}{ghi}"
local result = x:match(".-{.-}.-{(.-)}")
print(result)
.- matches zero or more characters, non-greedy. The whole pattern .-{.-}.-{(.-)} captures what's between the second { and the second }.
Try also x:match(".-}{(.-)}"), which is simpler.
I would go about it in a different manner:
local i, x, result = 1, "{abc}{def}{ghi}"
for w in x:gmatch '{(.-)}' do
if i == 2 then
result = w
break
else
i = i + 1
end
end
print( result )
I'm trying to do a library in Lua with some function that manipulate strings.
I want to do a function that changes the letter case to upper only on odd characters of the word.
This is an example:
Input: This LIBRARY should work with any string!
Result: ThIs LiBrArY ShOuLd WoRk WiTh AnY StRiNg!
I tried with the "gsub" function but i found it really difficult to use.
This almost works:
original = "This LIBRARY should work with any string!"
print(original:gsub("(.)(.)",function (x,y) return x:upper()..y end))
It fails when the string has odd length and the last char is a letter, as in
original = "This LIBRARY should work with any strings"
I'll leave that case as an exercise.
First, split the string into an array of words:
local original = "This LIBRARY should work with any string!"
local words = {}
for v in original:gmatch("%w+") do
words[#words + 1] = v
end
Then, make a function to turn words like expected, odd characters to upper, even characters to lower:
function changeCase(str)
local u = ""
for i = 1, #str do
if i % 2 == 1 then
u = u .. string.upper(str:sub(i, i))
else
u = u .. string.lower(str:sub(i, i))
end
end
return u
end
Using the function to modify every words:
for i,v in ipairs(words) do
words[i] = changeCase(v)
end
Finally, using table.concat to concatenate to one string:
local result = table.concat(words, " ")
print(result)
-- Output: ThIs LiBrArY ShOuLd WoRk WiTh AnY StRiNg
Since I am coding mostly in Haskell lately, functional-ish solution comes to mind:
local function head(str) return str[1] end
local function tail(str) return substr(str, 2) end
local function helper(str, c)
if #str == 0 then
return ""
end
if c % 2 == 1 then
return toupper(head(str)) .. helper(tail(str),c+1)
else
return head(str) .. helper(tail(str), c+1)
end
end
function foo(str)
return helper(str, 1)
end
Disclaimer: Not tested, just showing the idea.
And now for real, you can treat a string like a list of characters with random-access with reference semantics on []. Simple for loop with index should do the trick just fine.
I have a string stored in sqlite database and I've assigned it to a var, e.g. string
string = "First line and string. This should be another string in a new line"
I want to split this string into two separated strings, the dot (.) must be replace with (\n) new line char
At the moment I'm stuck and any help would be great!!
for row in db:nrows("SELECT * FROM contents WHERE section='accounts'") do
tabledata[int] = string.gsub(row.contentName, "%.", "\n")
int = int+1
end
I tried the other questions posted here in stachoverflow but with zero luck
What about this solution:`
s = "First line and string. This should be another string in a new line"
a,b=s:match"([^.]*).(.*)"
print(a)
print(b)
Are you looking to actually split the string into two different string objects? If so maybe this can help. It's a function I wrote to add some additional functionality to the standard string library. You can use it as-is or rename it to what ever you like.
--[[
string.split (s, p)
====================================================================
Splits the string [s] into substrings wherever pattern [p] occurs.
Returns: a table of substrings or, if no match is made [nil].
--]]
string.split = function(s, p)
local temp = {}
local index = 0
local last_index = string.len(s)
while true do
local i, e = string.find(s, p, index)
if i and e then
local next_index = e + 1
local word_bound = i - 1
table.insert(temp, string.sub(s, index, word_bound))
index = next_index
else
if index > 0 and index <= last_index then
table.insert(temp, string.sub(s, index, last_index))
elseif index == 0 then
temp = nil
end
break
end
end
return temp
end
Using it is very simple, it returns a tables of strings.
Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio
> s = "First line and string. This should be another string in a new line"
> t = string.split(s, "%.")
> print(table.concat(t, "\n"))
First line and string
This should be another string in a new line
> print(table.maxn(t))
2