数组索引超出界限

Question

private void PrintTable(DataTable table)
{ 
    foreach (DataRow row in table.Rows)
    {
        litCanCount.Text = "Canoe count is: ";
        litKayCount.Text = "Kayak count is: ";

        string currRow = row["CraftType"].ToString();
        if (currRow == CANOE)
        {
            Response.Write("CANOE INCREMENT!<br />");
            CANOEi++;
            txtCanCount.Text = CANOEi.ToString();
            arr[i] = currRow;
            i++;
        }
        if (currRow == KAYAK)
        {
            Response.Write("KAYAK INCREMENT!<br />");
            KAYAKi++;
            txtKayCount.Text = KAYAKi.ToString();
            arr[i] = currRow;
            i++;
        }
        for (int a = 0; arr.Length > a; a++)
        {
            Response.Write(arr[a] + "<br />");
        }
    }
}

public partial class Index: System.Web.UI.Page
{
    string CANOE = "Canoe";
    string KAYAK = "Kayak";
    int CANOEi;
    int KAYAKi;
    string[] arr = new string[] { };
    int i = 0;
}

Answer 1

我不认为你需要密码。如果您只想显示独木舟和皮艇的计数，您可以使用基本调用来选择

    DataRow[] canoe = table.Select("CraftType = 'Canoe'");
    DataRow[] kayak = table.Select("CraftType = 'Kayak'");

    litCanCount.Text = "Canoe count is: " + canoe.Length;
    litKayCount.Text = "Kayak count is: " + kayak.Length;

如果您考虑一下，那么datatable只是一个复杂的数组，框架提供了许多处理datatable的方法。

例如,在LINQ中

int canoeNumber = table.AsEnumerable().Count(x => x["CraftType"].ToString() == "Canoe");