private void button1_Click(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    string[] name = new string[] { "もちふわパンケーキ", "あんぱん", "チョココロネ", "メロンパン" };
    int[] value = new int[] { 100, 100, 110, 120 };

    dt.Columns.Add("ID", typeof(string));
    dt.Columns.Add("Name", typeof(string));
    dt.Columns.Add("Value", typeof(int));

    for (int i = 0; i < 4; i++)
    {
        DataRow row = dt.NewRow();
        row["ID"] = i.ToString("0000");
        row["Name"] = name[i];
        row["Value"] = value[i];
        dt.Rows.Add(row);
    }
    dataGridView1.DataSource = dt;
}

private void button2_Click(object sender, EventArgs e)
{
    string[] name = new string[] { "もちふわパンケーキ", "あんぱん", "チョココロネ", "メロンパン" };
    int[] value = new int[] { 100, 100, 110, 120 };

    DataGridViewColumn colA = CreateDataGridViewTextBoxColumn("ID", "ID", 60, typeof(string));
    DataGridViewColumn colB = CreateDataGridViewTextBoxColumn("Name", "Name", 120, typeof(string));
    DataGridViewColumn colC = CreateDataGridViewTextBoxColumn("Value", "Value", 60, typeof(int));

    dataGridView1.DataSource = null;
    dataGridView1.Columns.Clear();
    dataGridView1.Columns.Add(colA);
    dataGridView1.Columns.Add(colB);
    dataGridView1.Columns.Add(colC);

    for (int i = 0; i < 4; i++)
    {
        dataGridView1.Rows.Add();
        dataGridView1.Rows[i].Cells["ID"].Value = i.ToString("0000");
        dataGridView1.Rows[i].Cells["Name"].Value = name[i];
        dataGridView1.Rows[i].Cells["Value"].Value = value[i];
    }
}
/// <summary>
/// DataGridViewのColumn型を作成します。
/// </summary>
/// <param name="name">列の名前</param>
/// <param name="header">列のヘッダー</param>
/// <param name="width">列の現在の幅</param>
/// <param name="type">列のセルの値のデータ型</param>
/// <returns>DataGridViewTextBoxColumnオブジェクト</returns>
private DataGridViewColumn CreateDataGridViewTextBoxColumn(string name, string header, int width, Type type)
{
    DataGridViewTextBoxColumn col = new DataGridViewTextBoxColumn();
    col.Name = name;
    col.DataPropertyName = name;
    col.HeaderText = header;
    col.ValueType = type;
    col.Width = width;
    return col;
}