Validate Image name and Size before upload in ASP.Net using C# and VB.Net

Hi ilanocf,

Please refer below sample.

HTML 

<asp:FileUpload ID="fuUpload" runat="server"/>
<asp:Button ID="btnUpload" runat="server" Text="Upload" OnClick="UploadFile"/>
<hr />
<asp:Image ID="Image1" runat="server"/>
<asp:Label ID="lblMessege" runat="server"></asp:Label>

Namespace

C#

using System.IO;

VB.Net

Imports System.IO

Code

C#

protected void UploadFile(object sender, EventArgs e)
{
    string folderPath = Server.MapPath("~/Files/");
    if (!Directory.Exists(folderPath))
    {
        Directory.CreateDirectory(folderPath);
    }

    if (!File.Exists(Server.MapPath("~/Files/") + Path.GetFileName(fuUpload.FileName)))
    {
        if (fuUpload.PostedFile.ContentLength < 102400)
        {
            fuUpload.SaveAs(folderPath + Path.GetFileName(fuUpload.FileName));
            Image1.ImageUrl = "~/Files/" + Path.GetFileName(fuUpload.FileName);
        }
        else
        {
            lblMessege.Text = "File size of is exceeding the limit.";
        }
    }
    else
    {
        lblMessege.Text = "File already exists.";
    }

VB.Net

Protected Sub UploadFile(ByVal sender As Object, ByVal e As EventArgs)
    Dim folderPath As String = Server.MapPath("~/Files/")
    If Not Directory.Exists(folderPath) Then
        Directory.CreateDirectory(folderPath)
    End If

    If Not File.Exists(Server.MapPath("~/Files/") + Path.GetFileName(fuUpload.FileName)) Then
        If fuUpload.PostedFile.ContentLength < 102400 Then
            fuUpload.SaveAs(folderPath & Path.GetFileName(fuUpload.FileName))
            Image1.ImageUrl = "~/Files/" & Path.GetFileName(fuUpload.FileName)
        Else
            lblMessege.Text = "File size of is exceeding the limit."
        End If
    Else
        lblMessege.Text = "File already exists."
    End If
End Sub