労働時間を計算。DateDiff関数
Public Function fc_RoudouJikan(wStartTime As Date, wEndTime As Date) As Integer
'-----------------------------------------------------------------------------
' 調査日付と誕生日より年齢を計算する。
'-----------------------------------------------------------------------------
On Error GoTo Err_fc_RoudouJikan
Dim intRoudouJikan As Integer
intRoudouJikan = DateDiff("n", wStartTime, wEndTime)
'計算結果がマイナスのとき（日付をまたぐとき）は24時間（1440分）加算する
If intRoudouJikan < 0 Then
intRoudouJikan = intRoudouJikan + 1440
End If
fc_RoudouJikan = intRoudouJikan
Exit_fc_RoudouJikan:
Exit Function
Err_fc_RoudouJikan:
MsgBox ("fc_RoudouJikan:" & Err.Number & " " & Err.Description)
Resume Exit_fc_RoudouJikan
End Function