VBA Basic File I/O
VBA Basic File I/O
 VBA includes several objects, methods, and
functions that can be used for file I/O
 One possibility for file I/O
 The Workbook Object
 Its methods for saving and opening files
 If A VBA application requires File I/O
 It may Require
 A relatively small amount of data stored in
program variables
 NOT located in a worksheet or document
VBA Basic File I/O
 With Excel the programmer can copy the data
 To a worksheet
So the user can save the data in the usual way
 File  Save Menu Item
 Directly to a file (the contents of variables)
 More convenient to write directly to a file
 User does not need to be concerned with
the task
 Prevents the user from altering the data
before saving

VBA Basic File I/O
 In the Real World
 Many types of files are stored on a computers
hard drive



Operating System Files (Mac / Windows / Unix)
Image files
Application Files (Excel)
 Most are created by applications and are
proprietary
 Proprietary files should only be accessed by
the application form which they were created
VBA Basic File I/O
 Proprietary file have unique extension
 .accdb
 .xlsm
 .doc
 Etc………….
 The file extensions are used by the OS to identify the
application that created the file
 A proprietary file (like Excel) can contain
 Text and numerical information
 Formatting information (bold, font size and type)
 Non-textual information
 Images
 Charts
 Can only be opened by the application that created it
VBA Basic File I/O
 File I/O Using Workbook and Worksheet
Objects
 Contain methods for



Opening
Closing
Saving
 In the same manner a user might perform
these operations
 You can save workbook files in a variety of
formats with VBA code

The same file formats can save individual
worksheet information within a workbook
VBA Basic File I/O
 Opening and Saving Workbooks
 Use the Open() method of the Workbooks collection
object to open Excel-compatible files
 The Open() method has numerous arguments
 Only required argument
 Filename
 Syntax
 Workbooks.Open(FileName, UpdateLinks, ReadOnly,
Format, Password, WriteResPassword,
IgnoreReadOnlyRecommended, Origin, Delimiter,
Editable, Notify, Converter, AddToMru, Local,
CorruptLoad)
VBA Basic File I/O
 You will never use most of the arguments
 Unfamiliar names can be found in the online help
 The following statement opens a workbook named
myWorkbook.xlsm located in the same directory as
the active workbook
 Note: The active workbook must be previously saved or
the Path property of the Workbook object will not
return a valid file path
Dim filePath As string
filePath = ActiveWorkbook.Path
Workbooks.Open FileName:=filePath & “\myWorkbook.xlsm”
VBA Basic File I/O
 To save a workbook from a VBA program, use
 Save() method of the Workbooks collection
object
 SaveAs() method of the Workbook object
 The Save() method does not accept arguments
 Will save to the default directory
 The directory last used
 The directory specified in the General tab of
Excel’s Options dialog box
 If not previously saved
VBA Basic File I/O
VBA Basic File I/O

The SaveAs() method accepts many of the same
arguments as the Open() method of the
Workbooks collection object
 Most important


FileName
FileFormat
 Type
 .xlsm, .csv, .txt, and so on
 Should be specified as one of VBA’s defined xlFileFormat
constants
 Look in the object browser for a complete list
VBA Basic File I/O
VBA Basic File I/O
 Syntax for SaveAs() method
expression.SaveAs(FileName, FileFormat, Password,
WriteResPassword, ReadOnlyRecommended,
CreateBackup, AccessMode, ConflictResolution,
AddToMru, TextCodepage, TextVisualLayout, Local)
 The following code saves the active workbook to
the default directory as an Excel 2003 file
(xlWorkbookNormal)
ActiveWorkbook.SaveAs FileName:=“myWorkbook.xls”, FileFormat:=xlWorkbookNormal
VBA Basic File I/O
 You may also save data in a specific worksheet using the SaveAs()
method of the Worksheet object
 The two main arguments are


FileName
FileFormat
expression.SaveAs(FileName, FileFormat, Password,
WriteResPassword, ReadOnlyRecommended, CreateBackup,
AddToMru, TextCodepage, TextVisualLayout, Local)
 You cannot use SaveAs() method of the Worksheet object
to save the entire Workbook
 Only data within a specific worksheet.
VBA Basic File I/O
 Typically you save the content of a single worksheet as
some type of text file
 Comma-delimited
 Tab-delimited
 .html
 .xml
 And so on………..
 The following saves the data in an active worksheet to
a comma-delimited text file
ActiveSheet.SaveAs FileName:=“MyData.csv”, FileFormat:=xlCSV
VBA Basic File I/O
 Using VBA File I/O Methods
 In addition to the methods of the Workbooks, Workbook and
Worksheet Objects

Open(), Save(), SaveAs()
 VBA includes several more I/O objects such as the
 Dialogs, FileDialog, FileSystem, FileSystemObject
 and other subordinate objects
 Using the FileDialog Object
 The standard dialog used in Office applications for opening
and saving files
 Allows users to specify files and folders that a program should
use

Will return the paths of the selected files or folders
 You can also use the FileDialog object to execute the
associated action of the specified dialog box
VBA Basic File I/O
 A reference must be set to the
Microsoft Office object Library before
you can use the FileDialog object.
 From the VBA IDE select Tools,
References, and be sure to check the box
labeled Microsoft Office 12.0 Object
Library
VBA Basic File I/O
VBA Basic File I/O
 The fileDialog object contains two methods called
 Show()

Use the show() method to show one of four possible dialog
boxes depending on the constant passed to the fileDialog
property of the Application object
Dialog Type
Open
Save
File Picker
Folder Picker
VBA Constant(FileDialogType)
msoFileDialogOpen
msoFileDialogSaveAs
msoFileDialogFilePicker
msoFileDialogFolderPicker
Example:
Application.FileDialog(msoFileDialogOpen).Show
VBA Basic File I/O
 The execute() method enables the user to
 Carry out the specified action of the
dialog box
 For files compatable with Excel
 .xlsm, .xlt, .csv, …….
 For example
 The Open dialog box allows users to
select one or more files to open when the
Execute() method of the FileDialog
object is invoked
VBA Basic File I/O
 The FileDialogFilters and FileDialogSelectedItems
Collections
 The fileDialog object has two subordinate collection
objects
 FileDialogFilters


Collection object contains a collection of FileDialogFilter
objects
Represents the file extensions used to filter which files are
displayed
 Used with Open and SaveAs dialog boxes
VBA Basic File I/O
 Use the filters property of the FileDialog object to
return the FileDialogFilters collection
 Use the item property of the FileDialogFilters
collection object to return a FileDialogFilter object
 The Description and Extension properties of the
FileDialogFilter object return the description
 For example, All Files
 And the file extension used to filter the
displayed files
 For example (*.*)
VBA Basic File I/O
 CheckFileFilters() generates a list of all
possible file filters and their descriptions.
 Then outputs the lists via message boxes
 The Procedure loops through each
FileDialogFilter object in the
FileDialogFilters collection and
concantonates their Description and
Extension properties to separte string
variables.
VBA Basic File I/O
Public Sub cmdCheckFileFilters_Click()
'Use the Filters property of the FileDialog object to return a FileDialogFilters collection
'A collection of FileDialogFilter objects that represent the types of
'files that can be selected in a file dialog box that is displayed using
'the FileDialog object
Dim fileFilters As FileDialogFilters
'Represents a file filter in a file dialog box displayed through the FileDialog object.
'Each file filter determines which files are displayed in the file dialog box.
Dim fileFilter As FileDialogFilter
Dim i As Integer
Dim descrs As String
Dim xtns As String
Set fileFilters = Application.FileDialog(msoFileDialogOpen).Filters
'loop through a collection and build strings of
'all extensions and descriptions
For i = 1 To fileFilters.Count
Set fileFilter = fileFilters.Item(i)
'add carriage return and line feed to strings
descrs = descrs & fileFilter.Description & vbCrLf
xtns = xtns & fileFilter.Extensions & vbCrLf
Next i
MsgBox descrs
MsgBox xtns
End Sub
VBA Basic File I/O
 FileDialogSelectedItems collections object contains the
paths as strings to the files or folders selected by the user
 Use the SelectedItems property of the FileDialog object to
return the FileDialogSelectedItems collection
 The GetSelectedItem() sub procedure shows
 Open dialog
 Then loops through all items selected by the user
 To build the string containing the file path
 The file paths are outputed in a message box
 Note that the Item property of the
FileDialogSelectedItems object returns a string
VBA Basic File I/O
 You can use the Add() method of the FileDialogFilter collection
object to create your own list of filters
 The LoadImage() sub procedure shows the File Picker dialog box
after clearing the FileDialogFilters collection and adding two new
filters
 (*.*, and *.bmp)
 The Add() method requires a
 Description
 Extension
 Optional Position argument indicates the position of the added
filter in the list
VBA Basic File I/O
Public Sub cmdLoadImage_Click()
Dim fileDiag As FileDialog
Dim imgPath As String
Set fileDiag = Application.FileDialog(msoFileDialogFilePicker) ‘dialog box
With fileDiag
.AllowMultiSelect = False ‘User can only select one file
.Filters.Clear
.Filters.Add Description:="All files", Extensions:="*.*"
.Filters.Add Description:="Image", Extensions:="*.bmp", Position:=1
.FilterIndex = 1
‘sets which filter is selected when the dialog is show (essentially new)
.InitialFileName = ""
.Title = "Select BMP file“
‘called to display after properties are set
If .Show = -1 Then
'User pressed action button, open in this case
imagePath = .SelectedItems(1) ‘returns path to file selected
Sheet1.imgTest.Picture = LoadPicture(imagePath) ‘NOTE: you must add an image control & name
End If
End With
End Sub
VBA Basic File I/O
 If you use an execute() method of the FileDialog object
when selecting objects not compatible with Excel
 Will generate a runtime error or
 Open a workbook with unreadable data
 If AllowMultiSelect property is set to true
 User allowed to select multiple files

Open button
 Execute() method
 Attempts to open all selected files
VBA Basic File I/O
 The file system object
 Is a collection of methods that you can use to set and obtain
information about



Files
Directories
Drives
 The Open Statement
 Used to read / write data to a file
 The following table summarizes


the type of access
Modes or functions available

For reading / writing data to a file with VBA

VBA Basic File I/O
VBA Basic File I/O

The open statement requires several arguments, including

A string that designates the path to the specified file


Also requires an access mode






If the file does not exist then one will be created
Append
Binary
Input
Output
Random
And a file number

You can open multiple files in VBA programs, but they must be assigned unique file numbers
 Optional Paramaters include

An access parameter





Read
Write
Read / Write
Lock (used to restrict operations on a file from other programs)
Record length (specifies the length of the buffer or record)
 Open “C:\Data\Test.txt” for Input As #

This works if the file exists
1
VBA Basic File I/O
 Open “C:\Data\Test.txt” for Output As #1
 This will create a file for output if it does not already exist
 Sequential File Access
 Writing information to a squential access file is like recording music to a cassette tape
 Songs vary in length
 Recorded one after another
 Difficult to access a particular song (location)
 When writing to a sequential file
 Individual pieces of data are
 Usually stored in variables
 Vary in length
 Are written to the file one after another
“John Smith”, “111-2222”
“Joe James”, “123-4567”
“Jame Johnson”, “456-7890”
VBA Basic File I/O
“John Smith”, “111-2222”
“Joe James”, “123-4567”
“Jame Johnson”, “456-7890”
 Names and phone numbers were all written to the file as strings
 Enclosed in quotation marks
 Numeric values written to a sequential file will not contain quotation marks
 The strings containing names vary in length
 Require different amounts of memory for storage
 If access to part of a sequential file is desired at a later time
 i.e. Jame’s phone number

The entire file must be read into memory
 Its not possible to know the location of the disired component within the file
 After loading the enitre file has to be searched for the desired value
 This makes sequential access inefficient with very large files
 Squential access works good for small files
VBA Basic File I/O
 The CreateSeqFile() sub procedure
 Writes textual info form the first three rows
 In columns A & B of a worksheet to a sequential access file
Private Sub cmdSeqFile_Click()
Dim filePath As String
Dim i As Integer
filePath = ActiveWorkbook.path & "\SeqPhone.txt"
Open filePath For Output As #1
For i = 1 To 3
Write #1, Cells(i, "A").Value, Cells(i, "B").Value
Next i
Close #1
‘stop i/o
End Sub
VBA Basic File I/O
 Using Write # places quotation marks around each value written to the file
 Write # adds a new line character to the end of the last value written to the file
 Resulting in 3 new lines (loop executed 3 times)
 Because the structure of the file is know
 It’s a simple task to alter the procedure to read the data
Dim filePath As String
Dim i As Integer
Dim theName As String
Dim theNumber As String
i=1
filePath = ActiveWorkbook.path & "\SeqPhone.txt"
Open filePath For Input As #1
Do While Not EOF(1)
Input #1, theName, theNumber
Cells(i , “A”).value = theName
Cells(i , “B”).value = theNumber
i=i+1
Loop
Close #1
‘stop i/o
VBA Basic File I/O
 Random Access File
 Allow programmer to access specific values within the file without
loading the entire file into memory
 Accomplished by
 Ensuring the data elements are the same length before writing to the
file
 Consider the phone book example
 Instead of storing the information as variable length strings
 Store them as fixed length strings
 The combination of the two fixed-length strings that follow
require the same amount of memory for every line written to the
file
 This makes it easier to locate a particular line in the file when
the data is input
VBA Basic File I/O
Dim theName As String*20
Dim theNumber As String*8
 If the name to be stored is less than 20 characters
 Spaces are added to match the defined length
 If the name is greater than 20 characters, only the first 20 are stored

Important to define the string length for the largest input
 The resulting data file may look like this
“John Smith
“Joe James
“Jane Johnson
“, “111-2222”
“, “123-4567”
“, “454-7890”
VBA Basic File I/O
 Each line in the file requires the same amount of memory to store
 Referred to as a record
 Records can be represented by one or more values of the same or different
data types
 String, Integer, and so on
 Because the record lengths are identical, finding a specific record in a file
is relatively easy
 Without having to load the entire file
 Rather then declare the individual elements of a record as separate variables
 Define a custom data type that can be used in a variable declaration
 The variable of the newly defined data type can include all of the
elements of the record
VBA Basic File I/O

To define a phone record for the previous example, a custom data type that includes both string elements must be
declared in the general declarations section of a module.
Private Type Phone
theName as String*20
theNumber as String*20
End Type
‘the following code uses the above data type to write records to a file
Dim phoneRec As Phone
Dim filePath As String
Dim i As Integer, recNum As Integer
recNum = 1 'recordNumber must start with 1
filePath = ActiveWorkbook.path & "\randomPhone.dat"
Open filePath For Random As #1 Len = Len(phoneRec) 'specify the length of the record
For i = 1 To 3
phoneRec.theName = Cells(i, "A").Value
phoneRec.theNumber = Cells(i, "B").Value
Put #1, recNum, phoneRec 'Put writes data to the file (use Get to read data from a file)
recNum = recNum + 1
Next i
Close #1
VBA Basic File I/O
VBA Basic File I/O
VBA Basic File I/O
VBA Basic File I/O
VBA Basic File I/O
VBA Basic File I/O