Question

public partial class Form1 : Form
{
    public static Dictionary<string,string> contactList = new Dictionary<string,string>();
    public Form1()
    {
        InitializeComponent();
        Text = "My Telephone Directory";
    }

    private void txtAdd_Click(object sender, EventArgs e)
    {
        String name = txtName.Text;
        String teleNo = txtTelephone.Text;

        contactList.Add(name,teleNo);
        txtContactList.Text = "Added " + name;
    }

    private void txtClear_Click(object sender, EventArgs e)
    {
        txtContactList.Text = " ";
    }

    private void txtList_Click(object sender, EventArgs e)
    {

        String contactLists="";
        foreach (KeyValuePair<string,string> kvp in contactList)
        {

            contactLists += "Name: " + contactList.Keys.ToString()+ " Phone No: " + contactList.Values + Environment.NewLine;
        }
        txtContactList.Text = contactLists;
    }

    private void txtSearch_Click(object sender, EventArgs e)
    {

        String contactLists = "";


        foreach (KeyValuePair<string, string> kvp in contactList)
        {

            contactLists += "Name: " + contactList.Keys.ToString() + " Phone No: " + contactList.Values + Environment.NewLine;

            if (contactList.Keys.ToString() == txtName.Text)
            {

                contactLists += "Name: " + contactList.Keys.ToString() + " Phone No: " + contactList.Values.ToString() + Environment.NewLine;
            }
            txtContactList.Text = contactLists;

        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        OpenFileDialog openFileDialog1 = new OpenFileDialog();
    }

}

我无法枚举字典，请参阅txtList_Click事件处理程序。

如果我正在做什么，我得到System.Collections.Generic.Dictionary 2+KeyCollection[System.String,System.String] Phone No: System.Collections.Generic.Dictionary 2 + ValueCollection [System.String，System.String]。

如果我做contactList.Key就像我应该得到System.Collections.Generic.Dictionary

Answer 1

迭代字典并构建taskkill /f /im firefox.exe字符串

要迭代contactLists并构建字符串，只需使用您在Dictionary中指定的KeyValuePair变量（kvp）：

foreach

但是，在循环is inefficient中连接字符串foreach (KeyValuePair<string, string> kvp in contactList) { contactLists += "Name: " + kvp.Key + " Phone No: " + kvp.Value + Environment.NewLine; ...。 contactLists在这里会有所帮助，或者，您可以简单地计算出每个键值对＆＃34; string＆＃34;而不是循环。使用Linq Select，然后StringBuilder。

Join

重新搜索词典

使用Dictionary（或HashSet）的一个好处是它提供了索引/键控查找，因此您不需要通过手动比较键来迭代整个集合来查找元素。因此，如果您按照此人的姓名键入了电话号码，这将是一种更典型的用法：

var contactLists = 
    string.Join(Environment.NewLine,
        contactList.Select(cl => string.Format("Name: {0} Phone No: {1}",
                           cl.Key, cl.Value)));

为了使其更加强大，您需要先检查密钥是否存在，例如使用var searchPhone = contactList[txtName.Text];或ContainsKey：

TryGetValue

Answer 2

您正在调用集合对象上的ToString()方法，而不是特定的键和值对。试试这个：

foreach (KeyValuePair<string,string> kvp in contactList)
{
    contactLists += "Name: " + kvp.Key + " Phone No: " + kvp.Value + Environment.NewLine;
}

无法枚举字典keyvaluepair

2 个答案: