Add newline in ASP.Net GridView Header Text using C# and VB.Net

No it is not possible to add line break on DataTable column header.

While displaying like GridView, you can add line break.

Refer below example.

HTML

<asp:GridView ID="gvPivot" runat="server" OnRowCreated="OnRowCreated"></asp:GridView>

Namespaces

C#

using System.Data;

VB.Net

Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("test_name");
        dt.Columns.Add("test_weight", typeof(int));
        dt.Columns.Add("matrik", typeof(int));
        dt.Columns.Add("name", typeof(string));
        dt.Columns.Add("Final", typeof(int));
        dt.Columns.Add("Grade", typeof(string));
        dt.Columns.Add("Markah", typeof(int));
        dt.Rows.Add("name1", "100", "50", "John", "150", "A+", "75");
        dt.Rows.Add("name3", "100", "50", "John", "100", "A", "75");
        dt.Rows.Add("name2", "100", "75", "Robert", "200", "E", "75");
        gvPivot.DataSource = this.PivotData(dt);
        gvPivot.DataBind();
    }
}

protected void OnRowCreated(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.Header)
    {
        for (int i = 0; i < e.Row.Cells.Count; i++)
        {
            e.Row.Cells[i].Text = e.Row.Cells[i].Text.Replace(" (", "<br />");
        }
    }
}

private DataTable PivotData(DataTable sourceTable)
{
    DataTable pivotTable = new DataTable();
    pivotTable.Columns.Add("matrik", typeof(int));
    pivotTable.Columns.Add("name", typeof(string));

    // Extract unique TestName and TestWeight pairs and create columns for them
    var testNameWeights = sourceTable.AsEnumerable()
    .Select(row => new
    {
        TestName = row.Field<string>("test_name"),
        TestWeight = row.Field<int>("test_weight")
    })
    .Distinct()
    .ToList();

    foreach (var item in testNameWeights)
    {
        string columnName = $"{item.TestName} ({item.TestWeight})";
        pivotTable.Columns.Add(columnName, typeof(int));
    }

    pivotTable.Columns.Add("Final", typeof(int));
    pivotTable.Columns.Add("Grade", typeof(string));

    // Group data by MatricNo and Name
    var groupedData = sourceTable.AsEnumerable()
    .GroupBy(row => new
    {
        MatricNo = row.Field<int>("matrik"),
        Name = row.Field<string>("name"),
        Final = row.Field<int>("Final"),
        Grade = row.Field<string>("Grade")
    });

    // Populate pivot table
    foreach (var group in groupedData)
    {
        DataRow newRow = pivotTable.NewRow();
        newRow["matrik"] = group.Key.MatricNo;
        newRow["name"] = group.Key.Name;
        newRow["Final"] = group.Key.Final;
        newRow["Grade"] = group.Key.Grade;

        foreach (var row in group)
        {
            string testName = row.Field<string>("test_name");
            int testWeight = row.Field<int>("test_weight");
            string columnName = $"{testName} ({testWeight})";
            newRow[columnName] = row.Field<int>("Markah");
        }
        pivotTable.Rows.Add(newRow);
    }
    return pivotTable;
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As DataTable = New DataTable()
        dt.Columns.Add("test_name")
        dt.Columns.Add("test_weight", GetType(Integer))
        dt.Columns.Add("matrik", GetType(Integer))
        dt.Columns.Add("name", GetType(String))
        dt.Columns.Add("Final", GetType(Integer))
        dt.Columns.Add("Grade", GetType(String))
        dt.Columns.Add("Markah", GetType(Integer))
        dt.Rows.Add("name1", "100", "50", "John", "150", "A+", "75")
        dt.Rows.Add("name3", "100", "50", "John", "100", "A", "75")
        dt.Rows.Add("name2", "100", "75", "Robert", "200", "E", "75")
        gvPivot.DataSource = Me.PivotData(dt)
        gvPivot.DataBind()
    End If
End Sub
 
Protected Sub OnRowCreated(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
    If e.Row.RowType = DataControlRowType.Header Then
 
        For i As Integer = 0 To e.Row.Cells.Count - 1
            e.Row.Cells(i).Text = e.Row.Cells(i).Text.Replace(" (", "<br />")
        Next
    End If
End Sub
 
Private Function PivotData(ByVal sourceTable As DataTable) As DataTable
    Dim pivotTable As DataTable = New DataTable()
    pivotTable.Columns.Add("matrik", GetType(Integer))
    pivotTable.Columns.Add("name", GetType(String))
    Dim testNameWeights = sourceTable.AsEnumerable().[Select](Function(row) New With {Key
        .TestName = row.Field(Of String)("test_name"), Key
        .TestWeight = row.Field(Of Integer)("test_weight")
    }).Distinct().ToList()
 
    For Each item In testNameWeights
        Dim columnName As String = $"{item.TestName} ({item.TestWeight})"
        pivotTable.Columns.Add(columnName, GetType(Integer))
    Next
 
    pivotTable.Columns.Add("Final", GetType(Integer))
    pivotTable.Columns.Add("Grade", GetType(String))
    Dim groupedData = sourceTable.AsEnumerable().GroupBy(Function(row) New With {Key
        .MatricNo = row.Field(Of Integer)("matrik"), Key
        .Name = row.Field(Of String)("name"), Key
        .Final = row.Field(Of Integer)("Final"), Key
        .Grade = row.Field(Of String)("Grade")
    })
 
    For Each group In groupedData
        Dim newRow As DataRow = pivotTable.NewRow()
        newRow("matrik") = group.Key.MatricNo
        newRow("name") = group.Key.Name
        newRow("Final") = group.Key.Final
        newRow("Grade") = group.Key.Grade
        For Each row In group
            Dim testName As String = row.Field(Of String)("test_name")
            Dim testWeight As Integer = row.Field(Of Integer)("test_weight")
            Dim columnName As String = $"{testName} ({testWeight})"
            newRow(columnName) = row.Field(Of Integer)("Markah")
        Next
 
        pivotTable.Rows.Add(newRow)
    Next
    Return pivotTable
End Function

creenshot