private void btnActualizar_Click(object sender, EventArgs e)
        {
            if (dgwStudents.SelectedRows.Count > 0)
            {
                DataGridViewSelectedRowCollection rows = dgwStudents.SelectedRows;

                DataGridViewRow row = rows[0];

                Estudiante student = new Estudiante();
                student.Id       = Convert.ToInt32(row.Cells["id"].Value);
                student.Nombre   = (String)row.Cells["nombre"].Value;
                student.Carnet   = (String)row.Cells["carnet"].Value;
                student.Apellido = (String)row.Cells["apellido"].Value;
                student.Edad     = Convert.ToInt32(row.Cells["edad"].Value);
                student.Sexo     = (string)row.Cells["sexo"].Value;

                AddStudent addForm = new AddStudent(student);
                addForm.ShowDialog(this);
            }
        }
        private void btnAgregar_Click(object sender, EventArgs e)
        {
            AddStudent addForm = new AddStudent();

            addForm.ShowDialog(this);
        }