winforms - How can merge a particular column header in DataGridView C#?

Question

I would like to take a column header text for tow columns. How would you do this? Like this

| FULL NAME |

| first | last

---

I show First & last in one column

Answer 1

public partial class MergeRowHeaderForm5 : Form
{
    public MergeRowHeaderForm5()
    {
        InitializeComponent();
    }

    private void MergeRowHeaderForm5_Load(object sender, EventArgs e)
    {
        this.dataGridView1.Columns.Add("JanWin", "Win");
        this.dataGridView1.Columns.Add("JanLoss", "Loss");
        this.dataGridView1.Columns.Add("FebWin", "Win");
        this.dataGridView1.Columns.Add("FebLoss", "Loss");
        this.dataGridView1.Columns.Add("MarWin", "Win");
        this.dataGridView1.Columns.Add("MarLoss", "Loss");
        this.dataGridView1.Columns.Add("AprWin", "Win");
        this.dataGridView1.Columns.Add("AprLoss", "Loss");
        this.dataGridView1.Columns.Add("MayWin", "Win");
        this.dataGridView1.Columns.Add("MayLoss", "Loss");

        for (int j = 0; j < this.dataGridView1.ColumnCount; j++)
        {
            this.dataGridView1.Columns[j].Width = 45;
        }

        this.dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.EnableResizing;
        this.dataGridView1.ColumnHeadersHeight = this.dataGridView1.ColumnHeadersHeight * 2;
        this.dataGridView1.ColumnHeadersDefaultCellStyle.Alignment = DataGridViewContentAlignment.BottomCenter;
        this.dataGridView1.CellPainting += new DataGridViewCellPaintingEventHandler(dataGridView1_CellPainting);
        this.dataGridView1.Paint += new PaintEventHandler(dataGridView1_Paint);
        this.dataGridView1.Scroll += new ScrollEventHandler(dataGridView1_Scroll);
        this.dataGridView1.ColumnWidthChanged += new DataGridViewColumnEventHandler(dataGridView1_ColumnWidthChanged);
    }


    private void dataGridView1_ColumnWidthChanged(object sender, DataGridViewColumnEventArgs e)
    {
        Rectangle rtHeader = this.dataGridView1.DisplayRectangle;
        rtHeader.Height = this.dataGridView1.ColumnHeadersHeight / 2;
        this.dataGridView1.Invalidate(rtHeader);
    }

    private void dataGridView1_Scroll(object sender, ScrollEventArgs e)
    {
        Rectangle rtHeader = this.dataGridView1.DisplayRectangle;
        rtHeader.Height = this.dataGridView1.ColumnHeadersHeight / 2;
        this.dataGridView1.Invalidate(rtHeader);
    }

    private void dataGridView1_Paint(object sender, PaintEventArgs e)
    {
        string[] monthes = { "Emp Info", "", "", "", "" };
        for (int j = 0; j < 10; )
        {
            Rectangle r1 = this.dataGridView1.GetCellDisplayRectangle(j, -1, true);
            int w2 = this.dataGridView1.GetCellDisplayRectangle(j + 1, -1, true).Width;
            r1.X += 1;
            r1.Y += 1;
            r1.Width = r1.Width + w2 - 2;
            r1.Height = r1.Height / 2 - 2;
            e.Graphics.FillRectangle(new SolidBrush(this.dataGridView1.ColumnHeadersDefaultCellStyle.BackColor), r1);
            StringFormat format = new StringFormat();
            format.Alignment = StringAlignment.Center;
            format.LineAlignment = StringAlignment.Center;
            e.Graphics.DrawString(monthes[j / 2],
            this.dataGridView1.ColumnHeadersDefaultCellStyle.Font,
            new SolidBrush(this.dataGridView1.ColumnHeadersDefaultCellStyle.ForeColor),
            r1,
            format);
            j += 2;
        }
    }

    private void dataGridView1_CellPainting(object sender, DataGridViewCellPaintingEventArgs e)
    {
        if (e.RowIndex == -1 && e.ColumnIndex > -1)
        {
            Rectangle r2 = e.CellBounds;
            r2.Y += e.CellBounds.Height / 2;
            r2.Height = e.CellBounds.Height / 2;
            e.PaintBackground(r2, true);
            e.PaintContent(r2);
            e.Handled = true;
        }
    }
}