BinaryReader.ReadChars(Int32) 方法

定义

命名空间:

System.IO

程序集:

System.Runtime.dll

Source:

BinaryReader.cs

从当前流中读取指定的字符数，并以字符数组的形式返回数据，然后根据所使用的 Encoding 和从流中读取的特定字符，将当前位置前移。

public:
 virtual cli::array <char> ^ ReadChars(int count);

public virtual char[] ReadChars (int count);

abstract member ReadChars : int -> char[]
override this.ReadChars : int -> char[]

Public Overridable Function ReadChars (count As Integer) As Char()

参数

count

Int32

要读取的字符数。

返回

Char[]

包含从基础流中读取的数据的字节数组。 如果到达了流的末尾，则该字符数组可能小于所请求的字符数。

例外

ArgumentException

要读取的解码字符数大于 count。 如果 Unicode 解码器返回回退字符或代理项对，则可能发生此情况。

ObjectDisposedException

流已关闭。

IOException

出现 I/O 错误。

ArgumentOutOfRangeException

count 为负数。

示例

下面的代码示例演示如何使用内存作为后备存储来读取和写入数据。

using namespace System;
using namespace System::IO;
int main()
{
   array<Char>^invalidPathChars = Path::InvalidPathChars;
   MemoryStream^ memStream = gcnew MemoryStream;
   BinaryWriter^ binWriter = gcnew BinaryWriter( memStream );
   
   // Write to memory.
   binWriter->Write( "Invalid file path characters are: " );
   binWriter->Write( Path::InvalidPathChars );
   
   // Create the reader using the same MemoryStream 
   // as used with the writer.
   BinaryReader^ binReader = gcnew BinaryReader( memStream );
   
   // Set Position to the beginning of the stream.
   binReader->BaseStream->Position = 0;
   
   // Read the data from memory and write it to the console.
   Console::Write( binReader->ReadString() );
   Console::WriteLine( binReader->ReadChars( (int)(memStream->Length - memStream->Position) ) );
}

using System;
using System.IO;

class BinaryRW
{
    static void Main()
    {
        char[] invalidPathChars = Path.InvalidPathChars;
        MemoryStream memStream = new MemoryStream();
        BinaryWriter binWriter = new BinaryWriter(memStream);

        // Write to memory.
        binWriter.Write("Invalid file path characters are: ");
        binWriter.Write(Path.InvalidPathChars);

        // Create the reader using the same MemoryStream
        // as used with the writer.
        BinaryReader binReader = new BinaryReader(memStream);

        // Set Position to the beginning of the stream.
        memStream.Position = 0;

        // Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString());
        Console.WriteLine(binReader.ReadChars(
            (int)(memStream.Length - memStream.Position)));
    }
}

open System.IO

let invalidPathChars = Path.GetInvalidPathChars()
let memStream = new MemoryStream()
let binWriter = new BinaryWriter(memStream)

// Write to memory.
binWriter.Write "Invalid file path characters are: "
binWriter.Write invalidPathChars

// Create the reader using the same MemoryStream
// as used with the writer.
let binReader = new BinaryReader(memStream)

// Set Position to the beginning of the stream.
memStream.Position <- 0

// Read the data from memory and write it to the console.
printf $"{binReader.ReadString()}"
printfn $"{binReader.ReadChars(int (memStream.Length - memStream.Position))}"

Imports System.IO

Public Class BinaryRW

    Shared Sub Main()
    
        Dim invalidPathChars() As Char = Path.InvalidPathChars
        Dim memStream As new MemoryStream()
        Dim binWriter As New BinaryWriter(memStream)

        ' Write to memory.
        binWriter.Write("Invalid file path characters are: ")
        binWriter.Write(Path.InvalidPathChars)

        ' Create the reader using the same MemoryStream 
        ' as used with the writer.
        Dim binReader As New BinaryReader(memStream)

        ' Set Position to the beginning of the stream.
        memStream.Position = 0

        ' Read the data from memory and write it to the console.
        Console.Write(binReader.ReadString())
        Console.WriteLine(binReader.ReadChars( _
            CInt(memStream.Length - memStream.Position)))
    
    End Sub
End Class

注解

BinaryReader 读取操作失败后，不会还原文件位置。

从网络流读取时，在极少数情况下，如果 BinaryReader 是使用 Unicode 编码构造的，ReadChars则 方法可能会从流中读取额外的字符。 如果发生这种情况，可以使用 ReadBytes 方法读取固定长度的字节数组，然后将该数组传递给 ReadChars 方法。

另请参阅

• Encoding
• 文件和流 I/O
• 如何：从文件中读取文本
• 如何：将文本写入文件