Calculating Months

[dagoose]

Hi All,

I need to be able to calculate the age of a person in both years and months. The years I have sorted but the code for working out the number of months does not. It appears to work for the first 5 months but after that it goes weird.

'get the age in months
            Dim date1 As Date
            Dim date2 As Date
            Dim mnths As Integer
            Dim yrs As Integer
            Dim mnthcalc As Integer
            'set date to today
            date1 = Now
            date2 = dtDOB.Value
 
            mnths = DateDiff(DateInterval.Month, date2, date1)
            yrs = DateDiff(DateInterval.Year, date2, date1)
 
            If yrs = 0 Then
                txtMonths.Text = mnths
            Else
                'mnthcalc = yrs * 12
                'txtMonths.Text = (mnths - mnthcalc)
                mnthcalc = mnths / 12
                txtMonths.Text = mnthcalc
            End If

any help appreciated.

[jmcilhinney]

I'd suggest that you use the DateTime and TimeSpan structures to do this calculation rather than using the old DateDiff function. Haven't time to implement right now but I'll be back within a few hours.

[dagoose]

Cheers,
I haven't used those before, an example would be greatly appreciated.
Cheers

[jmcilhinney]

Actually, you lie. You have used the DateTime structure before because the in-built Date data type is actually implemented using the DateTime structure. Every Date object is a DateTime structure. We'll forget the TimeSpan for now as it's not needed for this example. Assuming that the person's date of birth is stored in a Date variable called dtDOB, you would get their current age in whole months like this:

Dim ageInMonths As Integer = (Date.Now.Year - dtDOB.Year) * 12 + (Date.Now.Month - dtDOB.Month)
 
        If Date.Now.Day < dtDOB.Day Then
            'The current month is yet to be completed.
            ageInMonths -= 1
        End If