如何打开一个文件并在TextBlock中显示它

所以我几乎只是从c#开始，我只是试图从。txt文件中获取文本，并在我的应用程序上显示它。我试过在任何地方寻找我能想到的，但我只发现人们这样做的控制台应用程序，当我尝试应用相同的解决方案，我只会给出错误。这就是我现在想要使用的，但我只是不断得到错误:"无法将'字符串'转换为'System.IO。为StreamReader(path)之后的路径设置流' ' '。我试过它作为一个控制台应用程序(改变输出代码)和工作良好

namespace FileOpenApp
{
   public sealed partial class MainPage : Page
   {
   public MainPage()
   {
       this.InitializeComponent();
   }
   private void inputSubmitButton_Click(object sender, RoutedEventArgs e)
       {
           outputBox.Text = "Testing";
           processFile();
       }
   private void processFile()
   {
       try
       {
           string path = @"C:'Users'Fabian'Dropbox'test.txt";
           using (StreamReader sr = new StreamReader(path)) //errors here
           {
               string line;
               while ((line = sr.ReadLine()) != null)
               {
                   outputBox.Text = line;
                   currentProcess.Text = "Done";
               }
           }
       }
       catch (Exception e)
       {
           currentProcess.Text = "Something went wrong";
       }
     }
   }
}

编辑:试图使用这个代码，我得到的错误，文件不存在于命名空间系统。IO

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Text;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;

namespace FileOpenApp
{
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            this.InitializeComponent();
        }
        private void inputSubmitButton_Click(object sender, RoutedEventArgs e)
            {
                outputBox.Text = "Testing";
                processFile();
            }
        private void processFile()
        {
            string path = @"C:'Users'Fabian'Dropbox'test.txt";
            string contents = "";
            System.IO.File.ReadAllText(path, contents);
            outputBox.Text = contents;
        }
    }
}

也试过;

string path = @"C:'Users'Fabian'Dropbox'test.txt";
outputBox.Text = File.ReadAllText(path);