如何：写入文本文件（C# 编程指南）-优快云博客

本文通过四个示例展示了如何使用C#的System.IO..::.File类进行文本文件的操作，包括写入完整字符串数组、单个字符串、部分字符串以及追加新文本。

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以下示例给出了将文本写入文件的各种方法。前两个示例使用 System.IO..::.File 类中的静态方法将完整的字符串数组或完整字符串写入文本文件。示例 #3 说明如果在将文本写入文件之前必须分别处理文本的每一行，应该如何将这些文本添加到文件中。示例 1-3 均覆盖文件中的所有现有内容。示例 #4 说明如何将文本追加到现有文件的末尾。

示例

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"};
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 structures, " +
"a class defines the data and behavior of the data type. ";
System.IO.File.WriteAllText(@"C:\Users\Public\TestFolder\WriteText.txt", text);
// Example #3: Write only some strings in an array to a file.
using (System.IO.StreamWriter file = new System.IO.StreamWriter(@"C:\Users\Public\TestFolder\WriteLines2.txt"))
{
foreach (string line in lines)
{
if (line.Contains("Second") == false)
{
file.WriteLine(line);
}
}
}
// Example #4: Append new text to an existing file
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 structures, 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
*/