对中英文不同字节进行：
function getStringCharCount(str)
local lenInByte = #str
local charCount = 0
local i = 1
while (i <= lenInByte)
do
local curByte = string.byte(str, i)
local byteCount = 1;
if curByte > 0 and curByte <= 127 then
byteCount = 1 --1字节字符
elseif curByte >= 192 and curByte < 223 then
byteCount = 2 --双字节字符
elseif curByte >= 224 and curByte < 239 then
byteCount = 3 --中文
elseif curByte >= 240 and curByte <= 247 then
byteCount = 4 --4字节字符
end
local char = string.sub(str, i, i + byteCount - 1)
i = i + byteCount -- 重置下一字节的索引
charCount = charCount + 1 -- 字符的个数（长度）
end
return charCount
end
