How to write a unicode symbol in lua - unicode

Question

How can I write a Unicode symbol in lua. For example I have to write symbol with 9658
when I write
string.char( 9658 );
I got an error. So how is it possible to write such a symbol.

Answer 1

Lua does not look inside strings. So, you can just write
mychar = "►"
(added in 2015)
Lua 5.3 introduced support for UTF-8 escape sequences:
The UTF-8 encoding of a Unicode character can be inserted in a literal string with the escape sequence \u{XXX} (note the mandatory enclosing brackets), where XXX is a sequence of one or more hexadecimal digits representing the character code point.
You can also use utf8.char(9658).

Answer 2

Here is an encoder for Lua that takes a Unicode code point and produces a UTF-8 string for the corresponding character:
do
local bytemarkers = { {0x7FF,192}, {0xFFFF,224}, {0x1FFFFF,240} }
function utf8(decimal)
if decimal<128 then return string.char(decimal) end
local charbytes = {}
for bytes,vals in ipairs(bytemarkers) do
if decimal<=vals[1] then
for b=bytes+1,2,-1 do
local mod = decimal%64
decimal = (decimal-mod)/64
charbytes[b] = string.char(128+mod)
end
charbytes[1] = string.char(vals[2]+decimal)
break
end
end
return table.concat(charbytes)
end
end
c=utf8(0x24) print(c.." is "..#c.." bytes.") --> $ is 1 bytes.
c=utf8(0xA2) print(c.." is "..#c.." bytes.") --> ¢ is 2 bytes.
c=utf8(0x20AC) print(c.." is "..#c.." bytes.") --> € is 3 bytes.
c=utf8(0x24B62) print(c.." is "..#c.." bytes.") --> 𤭢 is 4 bytes.

Answer 3

Maybe this can help you:
function FromUTF8(pos)
local mod = math.mod
local function charat(p)
local v = editor.CharAt[p]; if v < 0 then v = v + 256 end; return v
end
local v, c, n = 0, charat(pos), 1
if c < 128 then v = c
elseif c < 192 then
error("Byte values between 0x80 to 0xBF cannot start a multibyte sequence")
elseif c < 224 then v = mod(c, 32); n = 2
elseif c < 240 then v = mod(c, 16); n = 3
elseif c < 248 then v = mod(c, 8); n = 4
elseif c < 252 then v = mod(c, 4); n = 5
elseif c < 254 then v = mod(c, 2); n = 6
else
error("Byte values between 0xFE and OxFF cannot start a multibyte sequence")
end
for i = 2, n do
pos = pos + 1; c = charat(pos)
if c < 128 or c > 191 then
error("Following bytes must have values between 0x80 and 0xBF")
end
v = v * 64 + mod(c, 64)
end
return v, pos, n
end

Answer 4

To get broader support for Unicode string content, one approach is slnunicode which was developed as part of the Selene database library. It will give you a module that supports most of what the standard string library does, but with Unicode characters and UTF-8 encoding.