get max days of a month

[Chaos]

hi, i have a question how do i get max days of a month like this month has 31 max day ?

[Noki]

I don't believe there is a function that specifically gives you the number of months in a year. So we usually use a table to act as a database of sorts. However, we have to remember that there are leap years and that February has 29 days instead of the usual 28 on these years.

local months = { 
[1] = 31, 
[2] = 28, 
[3] = 31, 
[4] = 30, 
[5] = 31, 
[6] = 30, 
[7] = 31, 
[8] = 31, 
[9] = 30, 
[10] = 31, 
[11] = 30, 
[12] = 31, 
} 

 

This StackOverflow answer gives us some pseudo-code to calculate a leap year. Let's convert that to Lua.

 

function isLeapYear(year) 
    if ((year % 4 == 0) and (year % 100 ~= 0)) or (year % 400 == 0) then 
        return true 
    end 
    return false 
end 
  

function getMonthMaxDays(month, year) 
    if (months[month]) then 
        if (month ~= 2 and not isLeapYear(year)) then 
            return months[month] 
        else 
            return 29 
        end 
    end 
    return false 
end 

getMonthMaxDays(2, 2016) --> 29 
getMonthMaxDays(2, 2011) --> 28 
getMonthMaxDays(2, 2000) --> 29 
getMonthMaxDays(11, 1945) --> 30 

I also recommend using getRealTime.year to get the years since 1900. Just add 1900 onto that result to get the current year. That way the code will work years into the future!

Note: This is all untested.

Edit: Changed a few words and a couple of typos.