更新：2007 年 11 月
下列程式碼範例將示範如何從文字檔中讀取文字，第二個範例將告知您何時偵測到檔案結尾；您也可以使用 ReadAllLines 或 ReadAllText 方法來達成這項功能。
範例
Imports System
Imports System.IO
Class Test
Public Shared Sub Main()
Try
' Create an instance of StreamReader to read from a file.
Using sr As StreamReader = New StreamReader("TestFile.txt")
Dim line As String
' Read and display the lines from the file until the end
' of the file is reached.
Do
line = sr.ReadLine()
Console.WriteLine(Line)
Loop Until line Is Nothing
sr.Close()
End Using
Catch E As Exception
' Let the user know what went wrong.
Console.WriteLine("The file could not be read:")
Console.WriteLine(E.Message)
End Try
End Sub
End Class
using System;
using System.IO;
class Test
{
public static void Main()
{
try
{
// Create an instance of StreamReader to read from a file.
// The using statement also closes the StreamReader.
using (StreamReader sr = new StreamReader("TestFile.txt"))
{
String line;
// Read and display lines from the file until the end of
// the file is reached.
while ((line = sr.ReadLine()) != null)
{
Console.WriteLine(line);
}
}
}
catch (Exception e)
{
// Let the user know what went wrong.
Console.WriteLine("The file could not be read:");
Console.WriteLine(e.Message);
}
}
}
Option Explicit On
Option Strict On
Imports System
Imports System.IO
Public Class TextFromFile
Private Const FILE_NAME As String = "MyFile.txt"
Public Shared Sub Main()
If Not File.Exists(FILE_NAME) Then
Console.WriteLine("{0} does not exist.", FILE_NAME)
Return
End If
Using sr As StreamReader = File.OpenText(FILE_NAME)
Dim input As String
input = sr.ReadLine()
While Not input Is Nothing
Console.WriteLine(input)
input = sr.ReadLine()
End While
Console.WriteLine("The end of the stream has been reached.")
sr.Close()
End Using
End Sub
End Class
using System;
using System.IO;
public class TextFromFile
{
private const string FILE_NAME = "MyFile.txt";
public static void Main(String[] args)
{
if (!File.Exists(FILE_NAME))
{
Console.WriteLine("{0} does not exist.", FILE_NAME);
return;
}
using (StreamReader sr = File.OpenText(FILE_NAME))
{
String input;
while ((input=sr.ReadLine())!=null)
{
Console.WriteLine(input);
}
Console.WriteLine ("The end of the stream has been reached.");
sr.Close();
}
}
穩固程式設計
這個程式碼會建立一個 StreamReader，透過 File.OpenText 呼叫指向 MyFile.txt。StreamReader.ReadLine 會將每一行傳回為字串。當不再有字元可供讀取時，會顯示傳達該情形的訊息，並關閉資料流。
.gif "注意事項") 注意事項： |
|---|
Visual Basic 使用者可以選擇對檔案 I/O 使用 My.Computer.FileSystem 物件所提供的方法和屬性。如需詳細資訊，請參閱 My.Computer.FileSystem 物件。 |