Windows系统中使用C#读取文本文件内容的小示例

读取文本文件中的内容

此示例读取文本文件的内容以使用 System.IO.File 选件类的静态方法 ReadAllText 和 ReadAllLines。

class ReadFromFile
{
 static void Main()
 {
   // The files used in this example are created in the topic
   // How to: Write to a Text File. You can change the path and
   // file name to substitute text files of your own.

// Example #1
   // Read the file as one string.
   string text = System.IO.File.ReadAllText(@"C:\Users\Public\TestFolder\WriteText.txt");

// Display the file contents to the console. Variable text is a string.
   System.Console.WriteLine("Contents of WriteText.txt = {0}", text);

// Example #2
   // Read each line of the file into a string array. Each element
   // of the array is one line of the file.
   string[] lines = System.IO.File.ReadAllLines(@"C:\Users\Public\TestFolder\WriteLines2.txt");

// Display the file contents by using a foreach loop.
   System.Console.WriteLine("Contents of WriteLines2.txt = ");
   foreach (string line in lines)
   {
     // Use a tab to indent each line of the file.
     Console.WriteLine("\t" + line);
   }

// Keep the console window open in debug mode.
   Console.WriteLine("Press any key to exit.");
   System.Console.ReadKey();
 }
}

一次一行地读取文本文件
本示例使用 StreamReader 类的 ReadLine 方法将文本文件的内容读取（一次读取一行）到字符串中。所有文本行都保存在字符串 line 中并显示在屏幕上。

int counter = 0;
string line;

// Read the file and display it line by line.
System.IO.StreamReader file =
 new System.IO.StreamReader(@"c:\test.txt");
while((line = file.ReadLine()) != null)
{
 System.Console.WriteLine (line);
 counter++;
}

file.Close();
System.Console.WriteLine("There were {0} lines.", counter);
// Suspend the screen.
System.Console.ReadLine();