local input = "これは日本語の文字列です"
local count1 = input:len()
local count2 = #input
local _, count3 = string.gsub(input, "[^\128-\193]","")
local count4 = 0
for uchar in string.gmatch(input, "([%z\1-\127\194-\244][\128-\191]*)") do
    count4 = count4 + 1
end
local count5 = utf8len(input)
d(count1, count2, count3, count4, count5)

local MAX_SAVE_DATA_LENGTH = 2000 -- buffer length used by ZOS
local function WriteLongString(obj, key, value)
    local output = value
    local byteLength = #value
    if(byteLength > MAX_SAVE_DATA_LENGTH) then
        output = {}
        local startPos = 1
        local endPos = startPos + MAX_SAVE_DATA_LENGTH - 1
        while startPos <= byteLength do
            output[#output + 1] = string.sub(value, startPos, endPos)
            startPos = endPos + 1
            endPos = startPos + MAX_SAVE_DATA_LENGTH - 1
        end
    end
    obj[key] = output
end
 
local function ReadLongString(obj, key)
    local value = obj[key]
    if(type(value) == "table") then
        return table.concat(value, "")
    end
    return value
end