Split text (.txt) file into multiple files in ASP.Net using C# and VB.Net

Hi nirmal90,

Please refer below sample.

HTML

<asp:Button Text="Split File" ID="btnSplit" OnClick="SpitDataFiles" runat="server" />

Namespace

C#

using System.IO;

VB.Net

Imports System.IO

Code

C#

protected void SpitDataFiles(object sender, EventArgs e)
{
    string[] lines = File.ReadAllLines(Server.MapPath("~/Files/DataFiles.txt"));
    string fileData = string.Empty;
    for (int i = 0; i < lines.Length; i++)
    {
        string fileName = Server.MapPath("~/Files/DataFiles" + (i + 1) + ".txt");
        string line = lines[i];
        if (i == 0)
        {
            fileData += line + "\n";
        }
        else if (line.StartsWith("FILE") && i != 0)
        {
            File.WriteAllText(fileName, fileData);
            fileData = string.Empty;
            fileData += line + "\n";
        }
        else
        {
            fileData += line + "\n";
        }
        if (lines.Length == i + 1)
        {
            File.WriteAllText(fileName, fileData);
        }
    }
}        

VB.Net

Protected Sub SpitDataFiles(ByVal sender As Object, ByVal e As EventArgs)
    Dim lines As String() = File.ReadAllLines(Server.MapPath("~/Files/DataFiles.txt"))
    Dim fileData As String = String.Empty

    For i As Integer = 0 To lines.Length - 1
        Dim fileName As String = Server.MapPath("~/Files/DataFiles" & (i + 1) & ".txt")
        Dim line As String = lines(i)

        If i = 0 Then
            fileData += line & vbLf
        ElseIf line.StartsWith("FILE") AndAlso i <> 0 Then
            File.WriteAllText(fileName, fileData)
            fileData = String.Empty
            fileData += line & vbLf
        Else
            fileData += line & vbLf
        End If

        If lines.Length = i + 1 Then
            File.WriteAllText(fileName, fileData)
        End If
    Next
End Sub

Screenshot