VB6 用、日付に関する便利関数

Public Function 先月初日() As Date
    Dim 先月 As Date
    Let 先月 = DateSerial(Year(Now), Month(Now), 1) - 1
    先月初日 = DateSerial(Year(先月), Month(先月), 1)
End Function

Public Function 先月末日() As Date
    Dim 初日 As Date
    先月末日 = DateSerial(Year(Now), Month(Now), 1) - 1
End Function

Public Function 今月初日() As Date
    今月初日 = DateSerial(Year(Now), Month(Now), 1)
End Function

Public Function 今月末日() As Date
    Dim 来月 As Date
    Let 来月 = DateSerial(Year(Now), Month(Now), 1) + 31
    今月末日 = DateSerial(Year(来月), Month(来月), 1) - 1
End Function