lua 计算字符串字符个数“中文字算一个字符”

local function GetStringWordNum(str)
    local fontSize =
    local lenInByte = #str
    local count =
    local i =
    while true do
        local curByte = string.byte(str, i)
        if i > lenInByte then
            break
        end
        local byteCount =
        if curByte >  and curByte <  then
            byteCount =
        elseif curByte>= and curByte< then
            byteCount =
        elseif curByte>= and curByte< then
            byteCount =
        elseif curByte>= and curByte<= then
            byteCount =
        else
            break
        end
        -- local char = string.sub(str, i, i+byteCount-)
        i = i + byteCount
        count = count +
    end
    return count
end