Indexed files

[bplus]

Well the nice thing about Random Access is you deal directly with file so no worries about Saving after Open it but you do have to deal with fixed length lines.

So I made a very, very, very simple line editor for text files:
You enter a number not starting with 0 for line to see / edit
You enter a non number and rewrite the line
or you enter escape to quit and save the data to file.

I think I have all bugs out, let me know if you found one:

Code: (Select All)

_Title "Random Access text file" ' bplus 2023-11-04
Dim Shared MyFile$ ' name of text/data file being a text file you can use any editor to edit
MyFile$ = "Test File Index Access.txt"
Dim Shared NRecs ' Number of records
NRecs = 1
ReDim Shared MyArr$(1 To NRecs)
Width _DesktopWidth * .9 / 8
LoadFile
Dim As Long edit, rec
edit = -1
rec = 1
While edit
    Color 9
    Print
    Print "Rec Number:";
    Color 15
    Print rec
    Color 9
    Print "  Rec line: ";
    Color 15
    Print MyArr$(rec)
    Color 9
    Print
    Print "Enter number for record to read,"
    Print "Don't start numbers with 0."
    Print "enter non number to edit line,"
    Print "enter esc to quit..."
    Print
    Color 15
    Input u$
    If u$ <> "" Then
        If Asc(u$) = 27 Then
            edit = 0: Exit While
        ElseIf InStr("123456789", Left$(u$, 1)) Then
            test = Val(u$)
            If test > 0 Then
                If test >= NRecs Then enlargeMyArr test
                rec = test
            Else
                Beep
            End If
        ElseIf _Trim$(u$) <> "" Then
            MyArr$(rec) = u$
        End If
    End If
Wend
SaveFile
End

Sub enlargeMyArr (recs)
    If recs > UBound(MyArr$) Then ReDim _Preserve MyArr$(1 To recs): NRecs = recs
End Sub

' first thing to do for processing file data
Sub LoadFile ' loads file to working array with file lines as records
    If _FileExists(MyFile$) Then
        rec = 0
        Open MyFile$ For Input As #1
        While Not EOF(1)
            Line Input #1, r$
            rec = rec + 1
            If rec > UBound(MyArr$) Then ReDim _Preserve MyArr$(1 To rec)
            MyArr$(rec) = r$
        Wend
        Close #1
        NRecs = rec
    End If
End Sub

' last thing to do when done processing file data
Sub SaveFile ' saves myarr$ to file
    ' save a backup to MyFile$ in case something happens
    If _FileExists(MyFile$) Then
        Open MyFile$ For Input As #1
        Open "MyOldFileBackup.txt" For Output As #2
        While Not EOF(1)
            Line Input #1, r$
            Print #2, r$
        Wend
        Close
    End If
    Open MyFile$ For Output As #1
    For i = 1 To NRecs
        Print #1, MyArr$(i)
    Next
    Close #1
End Sub

Come to think @PhilOfPerth why not just use an editor?