Rename file name before saving if already exists in ASP.Net using C# and VB.Net

Hi samsmuthu,

Please refer below sample.

HTML

File Name:
<asp:TextBox ID="txtFileName" Text="SaharaDesert" runat="server" />
<br />
<asp:FileUpload ID="FileUpload1" runat="server" />
&nbsp;
<asp:Button ID="btnUpload" Text="Upload" runat="server" OnClick="btnUpload_Click" />
<asp:Label ID="LblDocumnet" runat="server" />
<asp:Label ID="LblFileContentType" runat="server" />
<asp:Label ID="LblFileSize" Text="size" runat="server" />
<asp:Label ID="LblError" runat="server" />

Namespace

C#

using System.IO;

VB.Net

Imports System.IO

Code

C#

protected void btnUpload_Click(object sender, EventArgs e)
{
    int count = 0;
    string folderName = txtFileName.Text.Replace(" ", "-");
    if (!Directory.Exists(Server.MapPath("~/") + folderName))
        Directory.CreateDirectory(Server.MapPath("~/") + folderName);

    string folderPath = Server.MapPath("~/") + folderName + @"\";
    bool fileOK = false;
    if (FileUpload1.HasFile)
    {
        string fileExtension;
        fileExtension = System.IO.Path.GetExtension(FileUpload1.FileName).ToLower();
        string[] allowedExtensions = new[] { ".jpeg", ".png", ".jpg" };
        for (int i = 0; i <= allowedExtensions.Length - 1; i++)
        {
            if (fileExtension == allowedExtensions[i])
                fileOK = true;
        }
        if (fileOK)
        {
            try
            {
                if (File.Exists(folderPath + txtFileName.Text.Replace(" ", "-") + fileExtension))
                {
                    string[] files = Directory.GetFiles(folderPath);
                    foreach (string filePath in files)
                    {
                        if (filePath.IndexOf(folderName + "_") != -1)
                        {
                            count++;
                        }
                    }
                    string UpFileName = txtFileName.Text.Replace(" ", "-") + "_" + count.ToString() + fileExtension;
                    FileUpload1.PostedFile.SaveAs(folderPath + UpFileName);
                    LblDocumnet.Text = UpFileName;
                    LblFileContentType.Text = FileUpload1.PostedFile.ContentType;
                    decimal size = Math.Round((System.Convert.ToDecimal(FileUpload1.PostedFile.ContentLength) / (decimal)System.Convert.ToDecimal(1024)), 2);
                    LblFileSize.Text = size.ToString();
                }
                else
                {
                    string UpFileName = txtFileName.Text.Replace(" ", "-") + fileExtension;
                    FileUpload1.PostedFile.SaveAs(folderPath + UpFileName);
                    LblDocumnet.Text = UpFileName;
                    LblFileContentType.Text = FileUpload1.PostedFile.ContentType;
                    decimal size = Math.Round((System.Convert.ToDecimal(FileUpload1.PostedFile.ContentLength) / (decimal)System.Convert.ToDecimal(1024)), 2);
                    LblFileSize.Text = size.ToString();
                }
            }
            catch (Exception ex)
            {
                LblError.Text = "File could not be uploaded.";
            }
        }
        else
        {
            LblError.Text = "Accept only .jpeg .png .jpg only";
            LblDocumnet.Text = "";
        }
    }
}

VB.Net

Protected Sub btnUpload_Click(ByVal sender As Object, ByVal e As EventArgs)
    Dim count As Integer = 0
    Dim folderName As String = txtFileName.Text.Replace(" ", "-")
    If Not Directory.Exists(Server.MapPath("~/") & folderName) Then
        Directory.CreateDirectory(Server.MapPath("~/") & folderName)
    End If

    Dim folderPath As String = Server.MapPath("~/") & folderName & "\"
    Dim fileOK As Boolean = False
    If FileUpload1.HasFile Then
        Dim fileExtension As String
        fileExtension = System.IO.Path.GetExtension(FileUpload1.FileName).ToLower()
        Dim allowedExtensions As String() = {".jpeg", ".png", ".jpg"}
        For i As Integer = 0 To allowedExtensions.Length - 1
            If fileExtension = allowedExtensions(i) Then
                fileOK = True
            End If
        Next
        If fileOK Then
            Try
                If File.Exists(folderPath & txtFileName.Text.Replace(" ", "-") & fileExtension) Then
                    Dim files As String() = Directory.GetFiles(folderPath)
                    For Each filePath As String In files
                        If filePath.IndexOf(folderName & "_") <> -1 Then
                            count += 1
                        End If
                    Next
                    Dim UpFileName As String = txtFileName.Text.Replace(" ", "-") & "_" & count.ToString() & fileExtension
                    FileUpload1.PostedFile.SaveAs(folderPath & UpFileName)
                    LblDocumnet.Text = UpFileName
                    LblFileContentType.Text = FileUpload1.PostedFile.ContentType
                    Dim size As Decimal = Math.Round((CDec(FileUpload1.PostedFile.ContentLength) / CDec(1024)), 2)
                    LblFileSize.Text = size
                Else
                    Dim UpFileName As String = txtFileName.Text.Replace(" ", "-") & fileExtension
                    FileUpload1.PostedFile.SaveAs(folderPath & UpFileName)
                    LblDocumnet.Text = UpFileName
                    LblFileContentType.Text = FileUpload1.PostedFile.ContentType
                    Dim size As Decimal = Math.Round((CDec(FileUpload1.PostedFile.ContentLength) / CDec(1024)), 2)
                    LblFileSize.Text = size
                End If
            Catch ex As Exception
                LblError.Text = "File could not be uploaded."
            End Try
        Else
            LblError.Text = "Accept only .jpeg .png .jpg only"
            LblDocumnet.Text = ""
        End If
    End If
End Sub

Screenshot