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:

Existence detection

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

Computer programming

Existence detection