How to copy/replace a file into a folder in VB.NET?

Question

I used File.Copy(source, target, True), where source is a full path name, like c:\source.txt and target is a folder, which may contain the same named file. I want to copy source.txt to a target folder and overwrite if the file already exists.

But I got the error:

'Target is a folder, not a file'

Answer 1

Target must contain a filename too:

sSource = "C:\something.txt"
sTarget = "C:\folder\something.txt"

File.Copy(sSource, sTarget, True)

If you want to programatically have the same filename just do:

File.Copy(sSource, Path.Combine(sFolder, Path.GetFileName(sSource)), True)

Read the MSDN Documentation to have examples and information about exceptions and use of the method.

Answer 2

You can also use a FileStream for reading and writing file contents. If you use a file stream you can read and write all types of binary files, not just text files.

Use the following procedure:

''' <summary>
    ''' copies a file from one location to another
    ''' </summary>
    ''' <param name="inputPath">full path to the input file</param>
    ''' <param name="outputPath">full path to the output file</param>
    ''' <param name="bufferSize">the size in bytes as an integer that will be read and written at a time from input file and to the output file</param>
    ''' <param name="overwrite">overwrite the output file if it already exists</param>
    ''' <returns></returns>
    Public Function CopyFile(ByVal inputPath As String,
                             ByVal outputPath As String,
                             ByVal bufferSize As Integer,
                             Optional ByVal overwrite As Boolean = False) As Boolean

        Dim PathIsClear As Boolean = True, SucOpt As Boolean = False
        Dim inputByteReaderObj As System.IO.FileStream = System.IO.File.Open(inputPath, IO.FileMode.Open) 'open a file stream for reading bytes from the input file
        Dim endofSize As Integer = My.Computer.FileSystem.GetFileInfo(inputPath).Length
        If overwrite AndAlso FileExists(outputPath) Then
            'if file exits, delete the output file
            PathIsClear = False
            PathIsClear = DeleteFilesOnDisk(outputPath) ' Delete the output file if it already exists
        End If

        ' Adjust array length for VB array declaration.

        Dim allBytesRead As Integer = 0, sucessfullBytes As Integer = 0, bytes As Byte() 'The byte array
        If bufferSize > endofSize Then
            bufferSize = endofSize
        End If
        If bufferSize >= 1 Then
            bytes = New Byte(bufferSize - 1) {} 'The byte array; create a byte array that will hold the data in length equal to the bufferSize; the array index starts at 0;
            If PathIsClear Then
                While inputByteReaderObj.Read(bytes, 0, bufferSize) > 0
                    'read bytes consequtively from the input file, each time read bytes equal in length to bufferSize
                    Try
                        My.Computer.FileSystem.WriteAllBytes(outputPath, bytes, True) ' Append to the file contents
                        sucessfullBytes += bufferSize
                    Catch ex As Exception
                        Stop
                    End Try
                    allBytesRead += bufferSize
                    If (allBytesRead + bufferSize) > endofSize Then
                        bufferSize = endofSize - allBytesRead 'change the size of the buffer match the end of the file
                    End If
                    If bufferSize >= 1 Then
                        bytes = New Byte(bufferSize - 1) {} 'the array index starts at zero, the bufferSize starts at 1
                    End If
                    If allBytesRead >= endofSize Or bufferSize = 0 Then
                        'the reader has already reached the end of file, exit the reader loop
                        Exit While
                    End If
                End While
                If sucessfullBytes = allBytesRead Then
                    SucOpt = True
                End If
            End If
        Else
            'write an empty file
            Try
                System.IO.File.Create(outputPath) 'Create an empty file because the size of the input file is zero
            Catch ex As Exception
                'an error occured in creating an empty file
            End Try
        End If

        inputByteReaderObj.Close()

        Return SucOpt
    End Function