Question

我正在尝试创建一个客户列表。当用户插入新客户端的名称时，必须将此名称添加到列表中并显示在消息框中。预先配置的客户是Jack，Sandra，Anna，Tom和Bob。当我运行以下脚本并输入新的客户端名称时，会弹出一个没有新名称的弹出窗口。这是为什么？

    private void btnAddClient_Click(object sender, EventArgs e)
    {

        string msg = "";

        List<string> Clients = new List<string>();
        Clients.Add("Jack");
        Clients.Add("Sandra");
        Clients.Add("Anna");
        Clients.Add("Tom");
        Clients.Add("Bob");

        foreach (string val in Clients)
        {
            msg += "- " + val + "\n";
        }

        if (txtAddClient.Text == "")
        {
            MessageBox.Show("No client name has been entered!");
        }
        else
        {
            string newClient = txtAddClient.Text;
            Clients.Add(newClient);
            MessageBox.Show(msg);
        }
    }

Answer 1

因为你没有在文本框中附加带有数据的msg变量。

循环遍历现有客户端并附加变量但是一旦确定文本框不为空，就将内容添加到列表并显示msg变量。您需要使用输入的数据附加msg变量。

参见@Tisho的代码示例如何实现它 - 不想将他的代码复制为我自己的代码

Answer 2

    private void btnAddClient_Click(object sender, EventArgs e)
    {

        string msg = "";

        List<string> Clients = new List<string>();
        Clients.Add("Jack");
        Clients.Add("Sandra");
        Clients.Add("Anna");
        Clients.Add("Tom");
        Clients.Add("Bob");

        if (txtAddClient.Text == "")
        {
            MessageBox.Show("No client name has been entered!");
        }
        else
        {
            string newClient = txtAddClient.Text;
            Clients.Add(newClient);

            // this is where you want to join your string
            // AFTER you add the new client to the list
            foreach (string val in Clients)
            {
                msg += "- " + val + "\n";
            }

            MessageBox.Show(msg);
        }
    }

Answer 3

更新：

private List<string> Clients = new List<string>(){ "Jack", "Sandra", "Anna", "Tom", "Bob"};

private void btnAddClient_Click(object sender, EventArgs e)
{
    string msg = "";

    if (txtAddClient.Text == "")
    {
        MessageBox.Show("No client name has been entered!");
    }
    else
    {
        string newClient = txtAddClient.Text;
        Clients.Add(newClient);
        foreach (string val in Clients)
        {
            msg += "- " + val + "\n";
        }
        MessageBox.Show(msg);
    }
}

Answer 4

你必须做

msg += txtAddClient.Text;

然后

MessageBox.Show(msg);

Answer 5

public partial class Form1 : Form
{
    List<string> Clients = new List<string>();

    public Form1()
    {
        InitializeComponent();
        Clients.Add("Jack");
        Clients.Add("Sandra");
        Clients.Add("Anna");
        Clients.Add("Tom");
        Clients.Add("Bob");
    }

    private void btnAddClient_Click(object sender, EventArgs e)
    {
        if (txtAddClient.Text == "")
        {
            MessageBox.Show("No client name has been entered!");
        }
        else
        {
            string msg = "";
            string newClient = txtAddClient.Text;
            Clients.Add(newClient);
            foreach (string val in Clients)
            {
                msg += "- " + val + "\n";
            }
            MessageBox.Show(msg);
        }
    }
}

未添加到列表中的新值（C＃）

5 个答案: