Consider the two cases below:
local str1 = "abc"
str1:len gives 3
local str2 = "£££"
str2:len gives 6
Can someone explain this?
LuaJit version: 5.1
2 Answers
The length of strings in Lua is the number of bytes in it, not the number of chars.
To handle multibyte charsets, you need a library like utf8, which is available in Lua 5.3.
4 Comments
user1691485
the issue I am facing is I need to support a string of length 80. So input with characters as '£' are exceeding the length as per lua, but not from the users perspective.
user1691485
local function parse_string(str) local ret = "" local flag = true for i = 1, #str do local c = str:sub(i,i) local char = string.char(b2i.toint(c, "big", false, 1)) if char > "\127" then flag = not flag if(flag) then ret = ret .. char end else ret = ret .. char end end return ret end
Tom Blodget
@user1681485 If users understand anything about the "length" of text, it would be graphemes and whitespace between visible characters. An artificial limit on your internal representation of their text would be quite difficult to explain precisely.
jocull
An example of using utf8 library would be a great addition to this answer :)
Found a solution.
local function parse_string(str)
local ret = ""
local flag = true
for i = 1, #str do
local c = str:sub(i,i)
local char = string.char(b2i.toint(c, "big", false, 1))
if char > "\127" then
flag = not flag
if(flag) then
ret = ret .. char
end
else
ret = ret .. char
end
end
return ret
end
local str2len = #str2:gsub("[\128-\191]", "")