How to convert string time to unix? - lua

Question

I'm creating an administrating tool and I need to convert string type like that: '1y2m3d4h5mi6s' to unixtime (seconds) in Lua. How can I make this?
I expect the output of StrToTime("1d") to be 86400.

Answer 1

function StrToTime(time_as_string)
local dt = {year = 2000, month = 1, day = 1, hour = 0, min = 0, sec = 0}
local time0 = os.time(dt)
local units = {y="year", m="month", d="day", h="hour", mi="min", s="sec", w="7day"}
for num, unit in time_as_string:gmatch"(%d+)(%a+)" do
local factor, field = units[unit]:match"^(%d*)(%a+)$"
dt[field] = dt[field] + tonumber(num) * (tonumber(factor) or 1)
end
return os.time(dt) - time0
end
print(StrToTime("1d")) -- 86400
print(StrToTime("1d1s")) -- 86401
print(StrToTime("1w1d1s")) -- 691201
print(StrToTime("1w1d")) -- 691200

Answer 2

Code snippet converting your date string to seconds
local testDate = '2019y2m8d15h0mi42s'
local seconds = string.gsub(
testDate,
'(%d+)y(%d+)m(%d+)d(%d+)h(%d+)mi(%d+)s',
function(y, mon, d, h, min, s)
return os.time{
year = tonumber(y),
month = tonumber(mon),
day = tonumber(d),
hour = tonumber(h),
min = tonumber(min),
sec = tonumber(s)
}
end
)
print(seconds)
You can also write a local function, I think it's a bit better to read.
local function printTime(y, mon, d, h, min, s)
local res = os.time{
year = tonumber(y),
month = tonumber(mon),
day = tonumber(d),
hour = tonumber(h),
min = tonumber(min),
sec = tonumber(s)
}
return res
end
local testDate = '2019y2m8d15h0mi42s'
local seconds = string.gsub(
testDate,
'(%d+)y(%d+)m(%d+)d(%d+)h(%d+)mi(%d+)s',
printTime
)
print(seconds)