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Existence checking or existence detection is an important aspect of many computer programs. An existence check before reading a file can catch and/or prevent a fatal error, for instance. For that reason, most programming language libraries contain a means of checking whether a file exists. An existence check can sometimes involve a "brute force" approach of checking all records for a given identifier, as in this Microsoft Excel Visual Basic for Applications code for detecting whether a worksheet exists: Function SheetExists(sheetName As String) As Boolean Dim sheetCount As Integer Dim t As Integer SheetExists = False sheetCount = ActiveWorkbook.SheetsCount For t = 1 To sheetCount If Sheets(t).Name = sheetName Then SheetExists = True Exit Function End If Next t End Function ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Existence detection」の詳細全文を読む スポンサード リンク
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