刷新DataGridViewComboBox项

Question

我试图刷新ComboBox中可用的天数。这是我创建的按钮，其中mindate和maxdate从DateTime Picker获取它们的值，Dia是DataGridViewComboBoxColumn但它不起作用。任何人都可以帮我找到问题的根源以及如何解决它。或者，如果你知道另一种方式，它也会有所帮助。 编辑：我说的按钮是button3。

public partial class InserirViagens : Form
{
    private DateTime mindate;
    private DateTime maxdate;
    public InserirViagens()
    {
        InitializeComponent();
        textBox1.Text = (Dados.agência.Viagens.Count + 1).ToString();
        textBox1.Enabled = false;
        dateTimePicker1.MinDate = DateTime.Now;
        dateTimePicker2.MinDate = DateTime.Now;
        mindate = dateTimePicker1.Value;
        maxdate = dateTimePicker2.Value;

    }

    private void button2_Click(object sender, EventArgs e)
    {
        this.Close();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        try
        {
            int cod = int.Parse(textBox1.Text);
            string des = textBox2.Text;
            double preço = double.Parse(textBox3.Text);
            DateTime inicio = dateTimePicker1.Value;
            DateTime fim = dateTimePicker2.Value;
            int contalinhas = (int)dataGridView1.RowCount-1;
            if (inicio<=fim)
            {
                Viagem v = new Viagem(cod, des, preço, inicio, fim);
                Dados.agência.Viagens.Add(cod, v);

                MessageBox.Show("Viagem Inserida com sucesso!\nContém " + contalinhas + " actividades.\n"+ Dados.dados.Viagens.Count + " Viagens existentes");
                this.Close();
            }
            else MessageBox.Show("Data de fim inválida!", "", MessageBoxButtons.OK, MessageBoxIcon.Warning);

        }
        catch(FormatException)
        {
            MessageBox.Show("Erro de formatação!", "", MessageBoxButtons.OK, MessageBoxIcon.Warning);


        }









    }

    private void dateTimePicker1_ValueChanged(object sender, EventArgs e)
    {

        mindate = dateTimePicker1.Value;


    }

    private void dateTimePicker2_ValueChanged(object sender, EventArgs e)
    {

        maxdate = dateTimePicker2.Value;

    }

    private void button3_Click(object sender, EventArgs e)
    {

       Dia.Items.Clear();
       while (mindate.DayOfYear < maxdate.DayOfYear)
       {
           Dia.Items.Add(mindate.Day + "/" + mindate.Month + "/" + mindate.Year);
           mindate.AddDays(1);
       }

    }
}

}

Answer 1

   Dia.Items.Clear();
   while (mindate.DayOfYear < maxdate.DayOfYear)
   {
       Dia.Items.Add(mindate.Day + "/" + mindate.Month + "/" + mindate.Year);
       mindatee.AddDays(1);
   }

mindatee.AddDays(1);不起作用。

AddDays方法信息

  

返回一个新的DateTime，它将指定的天数添加到   这个实例的价值。

因此它返回一个新的DateTime，并且不会更改旧的（在本例中为mindate）值。

<强>解决方案

在temp变量中保存mindate.AddDays（1）并将当前mindate替换为temp datetime值。

   Dia.Items.Clear();
   while (mindatee.DayOfYear < maxdatee.DayOfYear)
   {
       Dia.Items.Add(mindate.Day + "/" + mindate.Month + "/" + mindate.Year);
       var tempDate = mindate.AddDays(1);
       mindate = tempDate;
   }

如果您不想使用临时变量，您也可以在一行代码中执行此操作：

mindate = mindate.AddDays(1);

Answer 2

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    private void Btn_Click(object sender, EventArgs e)
    {
        DateTime minDate = Convert.ToDateTime(mindate.Value);
        DateTime maxDate = Convert.ToDateTime(maxdate.Value);

        foreach ( DataGridViewComboBoxColumn cmbCol in dataGridView1.Columns) {
            cmbCol.Items.Clear();

            while (minDate.Day < maxDate.Day) {
                cmbCol.Items.Add($"{minDate.Day}/{minDate.Month}/{minDate.Year}");
               minDate= minDate.AddDays(1);
            }
        }
    }
}