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.Sheets.Count
For t = 1 To sheetCount
If Sheets(t).Name = sheetName Then
SheetExists = True
Exit Function
End If
Next t
End Function
References
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