Manage different date formats in vb.net - vb.net

Question

I'm trying to figure out how best to handle different date formats that I might have as input.
The specific case is about the dates dd/MM/yyyy and MM/dd/yyyy.
At the time I try to convert the date as below:
firstDate = CDate("10/22/1988")
It obviously returns an error, how can I handle both cases in a generic way?

Answer 1

You can use Date.TryParseExact with the allowed format patterns:
Dim patterns As String() = {"dd/MM/yyyy", "MM/dd/yyyy"}
Dim dt As Date
Dim valid = Date.TryParseExact(str, patterns, CultureInfo.InvariantCulture, DateTimeStyles.None, dt)
Here a full working demo:
Sub Main
Dim inputs As String() = {"10/22/1988", "22/10/1988"}
Dim patterns As String() = {"dd/MM/yyyy", "MM/dd/yyyy"}
For Each str As String In inputs
Dim dt As Date
Dim valid = Date.TryParseExact(str, patterns, CultureInfo.InvariantCulture, DateTimeStyles.None, dt)
Console.WriteLine($"Valid: {valid} Date-Value: {dt}")
Next
End Sub
Output(i'm in germany):
Valid: True Date-Value: 22.10.1988 00:00:00
Valid: True Date-Value: 22.10.1988 00:00:00
In case of input like "3/5/1988" you should also allow:
"M/d/yyyy", "d/M/yyyy"
In this case the order is also the priority, so if both could work, the first wins.