changing a value to next value in an array - vb.net

Question

I am developing a routine to calculate the proper futures contract front month
If i have a array of integers denoting month numbers ie, "1,4,7,10,12"
and I have a variable integer that is 2.
How do i test the variable against the array and change the variable to the next highest available in the array if the variable itself wasn't in the array? ie in this case the variable's value of 2 would become 4.
I've tried various ways but am stuck now
If datenum >= (targetdayofmonth + adjdays) Then
currentmonth = currentmonth + 1
Dim currmonthname As String = MonthName(currentmonth, True)
For x As Integer = 0 To contractmonths.Count - 1
If GetMonthNumberfromShortMonthName(contractmonths(x)) = currentmonth Then
currmonthname = currmonthname
Else
End If
Next
Else
Dim currmonthname As String = MonthName(currentmonth, True)
End If
So based on Tim's comments I've updated the code to;
Dim contractmonthNos As New List(Of Int32)
For Each childnode As XmlNode In From childnode1 As XmlNode In root Where childnode1.SelectSingleNode("futures/symbol/Code").InnerText = commodcode
'get the available contract months for this contract
Dim contractmonthnodes As XmlNode = childnode.SelectSingleNode("ContractMonths")
contractmonthNos.AddRange(From subnode As XmlNode In contractmonthnodes Select GetMonthNumberfromShortMonthName(subnode.Name))
Next
If datenum >= (targetdayofmonth + adjdays) Then
currentmonth = currentmonth + 1
Dim currmonthname As String = MonthName(currentmonth, True)
Else
Dim nextmonth = From month As Integer In contractmonthNos Where month > currentmonth
If nextmonth.Any() Then
currentmonth = nextmonth.First()
End If
Dim currmonthname As String = MonthName(currentmonth, True)
End If
but I am getting a VS2012 squiggly under nextmonth in the If Then Else warning of "Possible multiple enumeration of IEnumerable"

Answer 1

I think this is what you want:
Dim intVar = 2
Dim months = { 1,4,7,10,12 }
Dim higherMonths = months.Where(Function(month) month > intVar).ToArray()
If higherMonths.Any() Then
intVar = higherMonths.First()
End If
If you don't want the next available month in the array but the nearest you have to sort before:
Dim higherMonths = months.Where(Function(m) m> intVar).
OrderBy(Function(m) m).
ToArray()
If higherMonths.Any() Then
intVar = higherMonths.First()
End If

Answer 2

Something like
Module Module1
Sub Main()
' N.B. this needs to the array to be sorted.
Dim a() As Integer = {1, 4, 7, 10, 12}
Dim toFind As Integer = 2
Dim foundAt As Integer = -1
For i = 0 To a.Length() - 1
If a(i) >= toFind Then
foundAt = i
Exit For
End If
Next
If foundAt >= 0 Then
Console.WriteLine(String.Format("Looked for {0}, found {1}.", toFind, a(foundAt)))
Else
Console.WriteLine(String.Format("Did not find {0} or higher.", toFind))
End If
Console.ReadLine()
End Sub
End Module
Or you might want to look at using the Array.BinarySearch Method.