Dot Net? : [轉貼]C# 讀寫 txt 檔的兩種方法介紹

class WriteTextFile
{
    static void Main()
    {

        // These examples assume a "C:\Users\Public\TestFolder" folder on your machine.
        // You can modify the path if necessary.

        // Example #1: Write an array of strings to a file.
        // Create a string array that consists of three lines.
        string[] lines = { "First line", "Second line", "Third line" };
        // WriteAllLines creates a file, writes a collection of strings to the file,
        // and then closes the file.
        System.IO.File.WriteAllLines(@"C:\Users\Public\TestFolder\WriteLines.txt", lines);


        // Example #2: Write one string to a text file.
        string text = "A class is the most powerful data type in C#. Like a structure, " +
                       "a class defines the data and behavior of the data type. ";
        // WriteAllText creates a file, writes the specified string to the file,
        // and then closes the file.
        System.IO.File.WriteAllText(@"C:\Users\Public\TestFolder\WriteText.txt", text);

        // Example #3: Write only some strings in an array to a file.
        // The using statement automatically closes the stream and calls
        // IDisposable.Dispose on the stream object.
        using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"C:\Users\Public\TestFolder\WriteLines2.txt"))
        {
            foreach (string line in lines)
            {
                // If the line doesn't contain the word 'Second', write the line to the file.
                if (!line.Contains("Second"))
                {
                    file.WriteLine(line);
                }
            }
        }

        // Example #4: Append new text to an existing file.
        // The using statement automatically closes the stream and calls
        // IDisposable.Dispose on the stream object.
        using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"C:\Users\Public\TestFolder\WriteLines2.txt", true))
        {
            file.WriteLine("Fourth line");
        }
    }
}
 //Output (to WriteLines.txt):
 //   First line
 //   Second line
 //   Third line

 //Output (to WriteText.txt):
 //   A class is the most powerful data type in C#. Like a structure, a class defines the data and behavior of the data type.

 //Output to WriteLines2.txt after Example #3:
 //   First line
 //   Third line

 //Output to WriteLines2.txt after Example #4:
 //   First line
 //   Third line
 //   Fourth line

using System;
using System.IO;
using System.Text;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        string mydocpath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
        StringBuilder sb = new StringBuilder();

        foreach (string txtName in Directory.EnumerateFiles(mydocpath,"*.txt"))
        {
            using (StreamReader sr = new StreamReader(txtName))
            {
                sb.AppendLine(txtName.ToString());
                sb.AppendLine("= = = = = =");
                sb.Append(sr.ReadToEnd());
                sb.AppendLine();
                sb.AppendLine();
            }
        }

        using (StreamWriter outfile = new StreamWriter(mydocpath + @"\AllTxtFiles.txt"))
        {
            outfile.Write(sb.ToString());
        }
    }
}

using System;
using System.Text;
using System.Windows;
using System.IO;

namespace WpfApplication
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }

        private async void AppendButton_Click(object sender, RoutedEventArgs e)
        {
            string mydocpath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
            StringBuilder sb = new StringBuilder();

            sb.AppendLine("New User Input");
            sb.AppendLine("= = = = = =");
            sb.Append(UserInputTextBox.Text);
            sb.AppendLine();
            sb.AppendLine();

            using (StreamWriter outfile = new StreamWriter(mydocpath + @"\UserInputFile.txt", true))
            {
                await outfile.WriteAsync(sb.ToString());
            }
        }
    }
}