C＃在“收藏夾”列表框中找到前三名

Question

查找前三名按鈕-處理數據以查找前三位的最高銷售額，並顯示這些銷售人員的姓名以及他們的位置（第一，第二，第三）和銷售額。

我有兩個列表框，我只想查找其銷售額最高的前3位銷售人員，並將其作為消息框顯示給用戶，分3行顯示

應用程序圖片： http : //s17.postimg.org/6dvo3a4qn/Untitled.jpg

列表框名稱：lstNames，lstTotalSales

我發現前3個按鈕代碼是：

private void btnFindTop3_Click(object sender, EventArgs e)
{
    decimal dec1HighestAmount = 0;
    decimal dec2HighestAmount = 0;
    decimal dec3HighestAmount = 0;
    for (int Index = 0; Index < lstTotalSales.Items.Count; Index++)
    {
        if (Convert.ToDecimal(lstTotalSales.Items[Index]) > dec1HighestAmount)
        {
            dec1HighestAmount = Convert.ToDecimal(lstTotalSales.Items[Index]);
        }
        if (Convert.ToDecimal(lstTotalSales.Items[Index]) < dec1HighestAmount)
        {
            dec2HighestAmount = Convert.ToDecimal(lstTotalSales.Items[Index]);
        }
        if (Convert.ToDecimal(lstTotalSales.Items[Index]) < dec2HighestAmount)
        {
            dec2HighestAmount = Convert.ToDecimal(lstTotalSales.Items[Index]);
        }
    }
    MessageBox.Show("Highest Amount is " + dec1HighestAmount + " and " + dec2HighestAmount + " and " + dec3HighestAmount);
}

這是我用來填充列表框的代碼：

public partial class Form1 : Form
{
    List<decimal> lstTotal = new List<decimal>();
    public Form1()
    {
        InitializeComponent();
    }

    private void btnReadInSalesData_Click(object sender, EventArgs e)
    {
        openFileDialog1.FileName = "SalesNumbers.txt";
        if (openFileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK) //If and Open Dialog OK
        {
            StreamReader srFile = File.OpenText(openFileDialog1.FileName);

            decimal decTotal = 0;

            while (!srFile.EndOfStream)
            {
                string strline = srFile.ReadLine();
                string[] strSplit = strline.Split('$');

                foreach (string strSplittedOutput in strSplit)
                {

                    if (decimal.TryParse(strSplittedOutput, out decTotal))
                    {
                        lstTotal.Add(decTotal);
                        lstTotalSales.Items.Add(strSplittedOutput);
                    }
                    else //else than decimals add strings
                    {
                        lstNames.Items.Add(strSplittedOutput); //add the Sales men names to lstNames listbox
                    }
                }
            } //End of while

            srFile.Close(); //Close StreamReader
        }
        else
            MessageBox.Show("User Cancel Read File Operation."); // if the user cancel the read file operation show this messagebox

        // ... ??
    }

    // ...
}

謝謝

Answer 1

就像是

var top_three = (from sales in lstTotalSales.Items
                 orderby sales descending
                 select sales).Take(3);

將使用linq保持您的前3名...

---

嗯...好吧...壞消息...您還有很多工作要做...好消息，這將使您走上正確的道路：

public partial class Form1 : Form
{
    List<decimal> lstTotal = new List<decimal>();
    List<SalesPerson> lstSalesPerson = new List<SalesPerson>;

    public Form1()
    {
        InitializeComponent();
    }

    private void btnReadInSalesData_Click(object sender, EventArgs e)
    {
        openFileDialog1.FileName = "SalesNumbers.txt";
        if (openFileDialog1.ShowDialog() == System.Windows.Forms.DialogResult.OK) //If and Open Dialog OK
        {
            StreamReader srFile = File.OpenText(openFileDialog1.FileName);

            decimal decTotal = 0;
            decimal tempSales =0;
            string tempName = "";

            while (!srFile.EndOfStream)
            {
                string strline = srFile.ReadLine();
                string[] strSplit = strline.Split('$');

                // I'll seriously assume this happens only twice ...
                foreach (string strSplittedOutput in strSplit)
                {

                    if (decimal.TryParse(strSplittedOutput, out decTotal))
                    {
                        lstTotal.Add(decTotal);
                        lstTotalSales.Items.Add(strSplittedOutput);
                        tempSales = strSplittedOutput;
                    }
                    else //else than decimals add strings
                    {
                        lstNames.Items.Add(strSplittedOutput); //add the Sales men names to lstNames listbox
                        tempName = strSplittedOutput;
                    }
                }

                    // Adding this to our people list ...
                    lstSalesPerson.Add(new SalesPerson {Name=tempName,TotalSales=tempSales});

            } //End of while

            srFile.Close(); //Close StreamReader
        }
        else
            MessageBox.Show("User Cancel Read File Operation."); // if the user cancel the read file operation show this messagebox

        // ... ??
    }

    // ...
}


public class SalesPerson {
    public string Name {get; set;}
    public decimal TotalSales {get; set;}
}

我添加了一個名為SalesPerson的類...該對象具有Name和TotalSales ... doooohhh ...在您的循環中，我假設您有一個帶有行的文本文件，並且每個名稱和銷售價值...最后，我已經添加了一個創建到您的lstSalesPerson （頂部添加）中的SalesPerson 。

現在我們快到了……請閱讀並理解本文： http : //www.codeproject.com/Articles/671544/Understanding-SelectedValue-SelectedValuePath-Sele 。

完成后，您將意識到不需要lstTotalSales和lstNames ，因為您只需將這些列表框鏈接到lstSalesPerson的DisplayMemberPath lstSalesPerson 。

現在，當您使用上面的linq選擇前3個對象時，就有3個對象。 對於每個對象，可以使用值Name和TotalSales因為它們只是該對象的屬性。

var top_three = (from person in lstSalesPerson
             orderby person.TotalSales descending
             select person).Take(3);

foreach (var person in top_three) {
     // do something with person.Name
     // do something with person.TotalSales
}