Excel vba for eof

Text files are a common source for storing and transporting information.

This topic will address access, key functions and ways to import and export this data with VBA.

VBA Open

To perform tasks with a text file in VBA you must first access it. We will do this through instruction Open.

Open requires parameters for:

• O pathname (directory or folder, and drive)
• O mode of access (Append, Binary, Input, Output, or Random)
• A filenumber of access (represented by a unique number per file)

    Open PathName For Mode As #FileNumber.

Each of these parameters will be detailed below.

File’s Path

You can assign the path name in two ways:

    PathName = "C:testdatabase.txt" 'Directly through folders path

    PathName = Application.GetOpenFilename() 'Through a dialog box selecting the file

The first form is used when the path does not change constantly. The second gives freedom, at each execution, to choose a different path.

Both of these forms will result in PathName associated with a String of the file location.

Mode

The mode must be one of the following commands:

Output — Used to write Excel content to the text file

Input — Used to read the file

Append — Used to add content to a file

Binary — Used to read and write data in a byte format

Random — Used to place characters of defined size

The focus of this tutorial will be only on: Input (import) and Output (export).

File Number

Each open file must contain a numbering, a number between 1 and 511 preceded by a hashtag #. Normally the numbering starts at #1 and follows successively #2…

Use the FreeFile statement to get the next available file number. If none is in use, FreeFile() will return 1.

Testing Open Instruction

The following code will access the file you selected with Application.GetOpenFilename()

Sub OpenTeste()

    Dim PathName As String

    PathName = Application.GetOpenFilename()
    'Opens the dialog box to select the file

    'Notice that PathName will be a path String E.g. "C:..."

    Dim FileNumber As Integer

    FileNumber  = FreeFile() 'Assigns the first available file number (E.g.: #1)

    Open PathName For Input As #FileNumber

    Close #FileNumber  'Closes the file (the number in FileNumber can be reused)
End Sub

Despite access, no information was imported or exported. To carry out these actions, we will need the help of the functions Input and Output respectively.

Import Text File

To import content from a text file into Excel we will use an example file called «database.txt» and the function Input:

Sub SimpleImport()

    Dim PathName As String

    PathName = Application.GetOpenFilename()
    'Opens the dialog box to select the file

    'Notice that PathName will be a path String E.g. "C:...database.txt"

    Dim FileNumber As Integer

    Open PathName For Input As #1 'File will be associated with the #1

    FirstCharacter = Input(1, #1) 'Collect 1 character from file # 1
    SecondCharacter = Input(1, #1) 'Collect 1 more character, this being the next one (the 2nd in this case)

    MsgBox FirstCharacter
    MsgBox SecondCharacter

    Close #1 'Close the file (number #1 to be reused)
End Sub

To collect all the characters at once we can use the LOF function:

Sub LOFimport()

    Dim PathName As String

    PathName = Application.GetOpenFilename()
    'Opens the dialog box to select the file

    'Notice that PathName will be a path String E.g. "C:...database.txt"

    Dim FileNumber As Integer

    Open PathName For Input As #1 'File will be associated with the #1

    MsgBox LOF(1)  'Total number of characters in file # 1

    Allcharacters = Input(LOF(1), #1) 'Collect all characters from file # 1

    MsgBox Allcharacters

    Close #1 'Close the file (number #1 to be reused)
End Sub

LOF returns the number of bytes of the file opened with Open. Because this is a text file, each byte is one character. Thus, the number of bytes will equal the number of characters.

To import the data into spreadsheet we can use the following code:

Sub TextImport ()
    Dim PathName As String
    Dim FileNumber As Integer
    Dim Textdata As String
    Dim BreakingLine as Variant
    Dim Lastline as Integer
    Dim Firstline as Integer

    'Opens the dialog box to select the file
    PathName = Application.GetOpenFilename()
    'Or enter a path with PathName = "C:FILE_LOCATIONdatabase.txt"

    FileNumber = FreeFile() 'Assigns the first available file number (E.g.: #1)

    Open PathName For Input As #FileNumber 'Open file in read mode

    'Copy the contents to Worksheet ---
    Textdata = Input(LOF(FileNumber), FileNumber) 'Loads all file contents into variable
    BreakingLine = Split(Textdata, vbCrLf) 'Creates a vector with each line of the file 
    Lastline = UBound(BreakingLine) 'Determines the last line of the vector
    Firstline = LBound(BreakingLine) 'Determines the first line of the vector
    'Transpose the vectors into the worksheet
    Range("A1").Resize((Lastline) - (Firstline) + 1).Value = Application.Transpose(BreakingLine)
    '----------------------------------
    Close #FileNumber 'Closes the file (the number in FileNumber can be reused)
End Sub

vbCrLf is a non-visible character CrLf indicates a line break in the file.

Main Functions Related to Open

    'Collect one by one
    Characters = Input(1, #1) 'Collect 1 character from file # 1
    Characters = Characters & Input(1, #1) 'Collect 1 more character, this being the next
    Characters = Characters & Input(1, #1) 'Collect 1 more character, this being the next
    '...

    'Loop with EOF support
    Characters = ""
    Do While Not EOF(1)
        Characters = Characters & Input(1, #1)
    Loop

    'Loop with BOF support
    Do While BOF(1)
        Characters = Characters & Input(1, #1)
    Loop

Export Text File

To export worksheet content to a text file:

Sub TextExport()

    Dim LastRow As Long
    Dim LastColumn As Long
    Dim NewFile As String
    Dim FileNumber As Integer
    Dim CellData As Variant

    FileNumber = FreeFile ' Assigns the first available file number (E.g.: #1)

    'Determines the last row of the worksheet with data
    LastRow = Cells(Rows.Count, 1).End(xlUp).Row

    'Determines the last column of the worksheet with data
    LastColumn = Cells(1, Columns.Count).End(xlToLeft).Column
    NewFile = "C:TestExport.txt" 'Use an existing folder

    'Exports the data from the worksheet to the created file
    Open NewFile For Output As #FileNumber 
    For i = 1 To LastRow
        For j = 1 To LastColumn
            If j = LastColumn Then
                CellData = CellData & Cells(i, j).Value
            Else
                CellData = CellData & Cells(i, j).Value & " "
            End If
        Next j
        Print #FileNumber, CellData
        CellData = ""
    Next i
    Close #FileNumber 'Saves and closes the text file with the data
End Sub

An error will occur if the folder you are saving the file does not already exist.

CSV File

A .csv file (Comma Separated Values) is, as the name suggests, a text file in which the items in each row are separated by commas, delimiting what should go in each column.

It is a very common type of file, and since each line refers several times to multiple columns, it may require a treatment with loops and functions, such as BOF and EOF.

Import CSV File

For ease of import, the Line Input instruction (which works line by line), rather than just Input (which works character by character).

Sub OpenTextToCSV()
    Dim PathName As String
    Dim FileNumber As Integer
    Dim FileRow As String
    Dim RowItem As Variant
    Dim LastRow As Long

    'Opens the dialog box to select the file
    PathName = Application.GetOpenFilename()
    'Or enter a path Ex: PathName = "C:testdatabase.txt"

    FileNumber = FreeFile ' Assigns the first available file number (Ex: #1)

    Open PathName For Input As #FileNumber 'Opens the file in read mode

    Do Until EOF(FileNumber)
        Line Input #FileNumber, FileRow
            RowItem = Split(FileRow, ", ")
            i = i + 1
            LastRow = UBound(RowItem)
            For j = 1 To LastRow + 1
                Cells(i, j).Value = RowItem(j - 1)
            Next
    Loop

    Close #FileNumber
End Sub

Export CSV File

Similar to exporting text, however mandatory the use of «, « in the separation of elements.

Sub SaveTextToCSV()

    Dim LastRow As Long
    Dim LastColumn As Long
    Dim NewFile As String
    Dim FileNumber As Integer
    Dim CellData As Variant

    FileNumber = FreeFile ' Assigns the first available file number (Ex: #1)

    'Determines the last row of the worksheet with data
    LastRow = Cells(Rows.Count, 1).End(xlUp).Row

    'Determines the last column of the worksheet with data
    LastColumn = Cells(1, Columns.Count).End(xlToLeft).Column
    NewFile = "C:TestExport.csv" 'Use an existing folder

    'Exports the data from the worksheet to the created file
    Open NewFile For Output As #FileNumber
        For i = 1 To LastRow
            For j = 1 To LastColumn
                If j = LastColumn Then
                    CellData = CellData & Cells(i, j).Value
                Else
                    CellData = CellData & Cells(i, j).Value & ", "
                End If
            Next j
            Print #FileNumber, CellData
            CellData = ""
        Next i
    Close #FileNumber 'Saves and closes the text file with the data
End Sub

An error will occur if the folder you are saving the file does not already exist.

EOF

EOF(FileNumber)

Функция EOF(End Of File) проверяет, достигнут ли конец файла. С помощью этой функции можно избежать ошибок, возникающих при попытках чтения или записи после достижения конца файла. Функция EOF возвращает значение False до тех пор, пока не будет достигнут конец файла. При использовании с файлами, открытыми в режиме Random или Binary, функция EOF возвращает значение True, если последней выполненной инструкции Get не удалось считать целую запись; в противном случае возвращается значение False.
Для файлов, открытых для доступа в режиме Binary, попытка чтения файла с помощью функции Input до возвращения функцией EOF значения True приводит к ошибке. При чтении двоичных файлов с помощью функции Input следует вместо функции EOF использовать функции LOF и Loc или использовать с функцией EOF инструкцию Get

Возвращаемое значение

Функция возвращает значение типа Integer, содержащее логическое значение True, при достижении конца файла
Примечание При обработке файлов, открытых с помощью Output, функция EOF всегда возвращает True

Параметры

FileNumber

Обязательный аргумент типа Integer, указывающий на любой допустимый номер файла

Пример

' В данном примере функция EOF
' используется для обнаружения конца файла. Предполагается,
' что MYFILE является текстовым файлом, который содержит
' несколько строк текста
Dim InputData
 ' Открываем файл для чтения
Open "MYFILE" For Input As #1
Do While Not EOF(1) ' Достигнут ли конец файла?
 Line Input #1, InputData ' Читаем строку данных
 Debug.Print InputData ' Выводим в окно отладки
Loop
' Закрываем файл
Close #1 

Категория
Функции работы с файлами

Named Arguments

EOF Function 249

Syntax

EOF( filenumber) filenumber

Use: Required

Data: Integer

Any valid file number.

Return Value

An integer containing -1 (True), or 0 (False). Description

Returns an integer evaluating to True (-1) when the end of a file has been reached; until the end of the file is reached, EOF returns False (0).

Rules at a Glance

• filenumber must be a valid number used in the Open statement to open either a random or sequential file.

• If you have opened the file using either random or binary access, a Get statement that can’t read a complete record (i.e., an attempt to access a record past the last record in the file) causes EOF to return True.

Example iFile = FreeFile

Open sFilename for Input as #iFile Do While Not EOF(iFile)

LineInput #iFile, sDataLine

Loop

Close #iFile Programming Tips & Gotchas

• EOF allows you to test whether the end of a file has been reached without generating an error.

• Because EOF dates back to the times when VB didn’t support an intrinsic Boolean data type, the function uses an integer data type to hold the 0 and -1 False and True values.

• Because you always write data to sequential files at the end of the file, the file marker is always at the end of the file, and EOF therefore always returns True when testing files opened with their modes set equal to either input or append.

• As Visual Basic is continually enhanced with new functions and new objects, there are more efficient and elegant alternatives to some of the VB language elements that have been with us since before «Visual» was even thought of! The following snippets compare methods of populating an array with data extracted from a comma-delimited text file. The first snippet uses a standard Do…Loop and EOF flag:

250 Chapter 7- The Language Reference

Dim sFilename As String Dim sContents As String Dim iFile As Integer

Dim sArray() As String iFile = FreeFile sFilename = «testinput.txt» ReDim sArray(0)

Open sFilename For Input As #1 Do While Not EOF(1)

Input #1, sContents

ReDim Preserve sArray(UBound(sArray) + 1) sArray(UBound(sArray)) = sContents Loop Close #1

You can replace this with a single call to the Input function, passing to it the length of the text file, and, if you’re using VB6, you can call the Split function to parse the comma-delimited string:

Dim sFilename As String Dim sContents As String Dim iFile As Integer

Dim sArray() As String sFilename = «testinput.txt»

Open sFilename For Input As #iFile sContents = Input(LOF(iFile), iFile) Close #iFile sArray = Split(sContents, «,»)

Again, for VB6 users only, there is the object-oriented way of extracting the data, again passing the resulting string to the Split function to be parsed. For this example to work, you have to create a project reference to the Microsoft Scripting Runtime Library, which gives you access to the File System Object:

Dim sFilename As String

Dim sArray() As String

Dim ofsFileSys As New Scripting.FileSystemObject Dim ofsTextStream As TextStream sFilename = «testinput.txt» Set ofsTextStream = _

ofsFileSys.OpenTextFile(sFilename) sArray = Split(ofsTextStream.ReadAll, «,») Set ofsTextStream = Nothing

• Don’t confuse the EOF Function with the EOF property of the RDO, DAO, and ADO recordsets and result sets. The former is a function for testing the position of the file pointer in a file opened using the VBA Open statement; the latter is a property that indicates the state of the record pointer in a database or recordset opened using automation.

• The AtEndOfStream property is the TextStream object’s equivalent to the EOF function.

EOF Function 251

See Also

File System Objects, Get Statement, Loc Function, LOF Function, Open Statement

Continue reading here: Erase Statement

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