TextReader class
https://docs.microsoft.com/zh-cn/dotnet/api/system.io.textreader?view=netframework-4.8
Namespace: System.IO
Assembly: mscorlib.dll
Represents a reader that can read ordered character series.
The TextReader class is an abstract class. So don't instantiate it in code. The StreamReader class is derived from TextReader and provides member implementations to read from the stream.
The TextReader class is used to read text files, and the StreamReader class is inherited by the TextReader class. The methods of the StreamReader class mainly include:
- Read reads the next character from the file stream;
- ReadLine reads a line of characters from the file stream;
- ReadToEnd reads from the current position of the file stream to the end of the stream;
- Peek, returns the next character in the file stream, but does not read this character.
There are two ways to create a StreamReader object, one is to create a file path name, and the other is to create a TextReader class from an already created file stream object.
The TextWriter class is used to rewrite the content of a text file, and the StreamWriter class is inherited by the TextWriter class.
The methods of the StreamWriter class include:
- Write write data to a text file;
- WriteLine write a line;
- Close, close the file stream and release resources.
The StreamWriter class can also construct objects in two ways, one is created by the file path name, and the other is created by the already created file stream object.
Module Module1
Sub Main()
testTextFile()
Console.Read()
End Sub
Private Sub testTextFile()
Dim TextLine As String = ""
Dim Fs As IO.FileStream
Dim Sw As IO.StreamWriter
Dim Sr As IO.StreamReader
Fs = New IO.FileStream("j:\test\TextReader.txt", IO.FileMode.OpenOrCreate, IO.FileAccess.Write)
Sw = New IO.StreamWriter(Fs)
Dim flag As Boolean = True
While flag
Console.WriteLine("输入一行字,回车键退出。")
TextLine = Console.ReadLine()
If TextLine = "" Then
flag = False
Else
Sw.WriteLine(TextLine)
End If
End While
Sw.Close()
Fs = New IO.FileStream("j:\test\TextReader.txt", IO.FileMode.Open, IO.FileAccess.Read)
Sr = New IO.StreamReader(Fs)
flag = True
While flag
If Sr.Peek = -1 Then
flag = False
Else
TextLine = Sr.ReadLine
Console.WriteLine(TextLine)
End If
End While
Sr.Close()
End Sub
End Module
