Question

假设允许用户从ListBox中选择一个团队，单击一个按钮并显示该团队通过引用.txt文件（称为World Series）赢得World Series的次数。

我正在尝试获取所选项目，并检查所选项目在World Series .txt文件中显示的次数。

任何指针？

    private void compareList()
    {
        StreamReader champFile = File.OpenText("WorldSeries.txt");
        List<string> champList = new List<string>();
        string selectedTeam;

        while (!champFile.EndOfStream)
        {
            champList.Add(champFile.ReadLine());
        }
        while (teamList.SelectedIndex != 0)
        {
            selectedTeam = teamList.SelectedItem.ToString();
        }
        if (selectedTeam = champList???)
        {
            MessageBox.Show("The " + selectedTeam + "has won the World Series " + champList.????.Count + "times! ")
        }
        else
        {
            MessageBox.Show("The " + selectedTeam + "has never won the World Series.")
        }
    }

Answer 1

if (teamList.SelectedIndex == -1)
{
   MessageBox.Show("Please select an Item first!");
   return;
}

string selectedTeam = teamList.SelectedItem.ToString();
var count = File.ReadAllLines("WorldSeries.txt").Where(line => line ==selectedTeam).Count();

//var count = champList.Where(l=>l==selectedTeam).Count();

if (count >0)
{
    MessageBox.Show("The " + selectedTeam + "has won the World Series " + count  + "times! ");
}
else
{
    MessageBox.Show("The " + selectedTeam + "has never won the World Series.")
}

Answer 2

您可以使用File.ReadLines和一些LINQ

selectedTeam = teamList.SelectedItem.ToString();
var count = File.ReadLines("WorldSeries.txt")
           .Count(x => x.Contains(selectedTeam));


if(count > 0)
{
   MessageBox.Show("The " + selectedTeam + "has won the World Series " +  count + "times! ")
}

Answer 3

你可以这样做

更新的代码

if(teamList.SelectedIndex != 0 && champList.Contains(SelectedTeam))
{
MessageBox.Show("The " + selectedTeam + "has won the World Series " + champList.Where(w => w == SelectedItem).Count() + "times! ");
}

Answer 4

将champList放在字典中并增加一个计数器（如果它们已经存在）。

private void compareList()
    {
        StreamReader champFile = File.OpenText("WorldSeries.txt");
        Dictionary<string, int> champList = new Dictionary<string, int>();
        string selectedTeam;
        string currentChamp;
        while (!champFile.EndOfStream)
        {
            currentChamp = champFile.ReadLine();
            if(champList.containsKey(currentChamp))
                champList.get(currentChamp) += 1;
            else
                champList.Add(champFile.ReadLine(), 1);
        }
        while (teamList.SelectedIndex != 0)
        {
            selectedTeam = teamList.SelectedItem.ToString();
        }
        if (champList.hasKey(selectedTeam))
        {
            MessageBox.Show("The " + selectedTeam + "has won the World Series " + champList.get(selectedTeam) + "times! ")
        }
        else
        {
            MessageBox.Show("The " + selectedTeam + "has never won the World Series.")
        }
    }

计算项目在列表C＃中显示的次数

4 个答案:

更新的代码