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Question

我有一个登录页面，我正在尝试让表单读取文本框中的内容+“。txt”，以便打开相应的页面。我已经设法首先检查它是否存在，但第二部分不起作用 - 不支持给出路径的错误消息出现在filePath +“。txt”

见下面的代码：

public bool check_user(string pUsername)
{
    //checks first to see if user exists

    using (StreamReader sr = new StreamReader(pUsername + ".txt"))
    {
        string line;
        while ((line = sr.ReadLine()) != null)
        {
            //read first bit of data from text file eg username, data split by ";"
            string[] data = line.Split(';');
            if (data[0] == pUsername)
            {
                MessageBox.Show("User found");
                return true;
            }
        }

        MessageBox.Show("User not found, try again");

        return false;
    }

}

private void btnLogin_Click(object sender, EventArgs e)
{
    //Read from file
    if (check_user(txtUsername.Text.Trim()))
    {

        string filePath = txtUsername + ".txt";
        using (StreamReader sr = new StreamReader(filePath + ".txt"))

        {
            string line;
            while ((line = sr.ReadLine()) != null)
            {
                //read first bit of data from text file eg username, data split by ";"
                string[] data = line.Split(';');
                if (data[0] == txtUsername.Text.Trim())
                {
                    break;
                }

            }

            // read second bit of data from text file eg password, data split by ";"
            string[] user = line.Split(';');
            if (user[1] == txtPassword.Text.Trim())
            {
                // checks access levels by viewing the third part of data and corresponds to which form to open
                if (user[2] == "employee")
                {
                    EmployeeForm frm = new EmployeeForm();
                    frm.Show();

                }
                else if (user[2] == "admin")
                {
                    AdminForm frm = new AdminForm();
                    frm.Show();

                }
            }
            else
            {
                MessageBox.Show("Login not successful, try again", "Error",
                    MessageBoxButtons.OK, MessageBoxIcon.Error);

            }
        }
    }
}

Answer 1

首先你这样做：

check_user(txtUsername.Text.Trim())

表示txtUsername是某种具有Text属性的控件。下面两行：

string filePath = txtUsername + ".txt";

这相当于

string filePath = txtUsername.ToString() + ".txt";

因为txtUsername不是字符串，而是某些具有Text属性的控件 - 最终会出现无效路径。将其更改为：

string filePath = txtUsername.Text.Trim() + ".txt";