Home  |  Delphi .net Home  |  System.IO.BinaryReader  |  ReadBytes Method
  
ReadBytes  
Method  
Reads the next block of bytes from the current stream
BinaryReader Class
System.IO NameSpace
CF1.  Function ReadBytes ( Count : Integer ) : Array of Byte;
CF : Methods with this mark are Compact Framework Compatible
Description
If the current stream has not been exhausted, up to Count bytes are returned.
 
The stream position is updated accordingly.
 
In the first syntax, the Read method returns the next stream character is returned as an integer. The integer value is the numeric equivalent of the character, or -1 if the string was exhausted.
 
In the second and third syntaxes, an attempt is made to read up to Count bytes/characters. These are overlaid onto the Bytes or Characters array as appropriate from StartIndex. The returned integer value is the number of bytes/characters overlaid. Zero if the string was already exhausted before the read.
Notes
You must set the length of the target Byte array, and it must have sufficient capacity to hold the returned bytes.

Compare with the more flexible Read method, where a block of stream characters can be read into an array at a specific array position.
Microsoft MSDN Links
System.IO
System.IO.BinaryReader
 Author links

 Buy Website Traffic at
 Buywebsitetrafficexperts.com

 Buy Proxies at
 Buyproxies.io
 
 
 
Reading blocks of bytes
program Project1;
{$APPTYPE CONSOLE}

uses
  System.IO;

var
  MyFileStream  : System.IO.FileStream;
  MyFileWriter  : System.IO.BinaryWriter;
  MyFileReader  : System.IO.BinaryReader;
  MyByteArray   : Array of Byte;
  i             : Integer;

begin
  // Create and open our binary file as a stream
  MyFileStream := System.IO.File.Open('C:DelphiBasics.txt',
                                      System.IO.FileMode.Create);

  // Create a BinaryWriter to allow writing to this file
  MyFileWriter := System.IO.BinaryWriter.Create(MyFileStream);

  // Write to the file
  MyFileWriter.Write(12);
  MyFileWriter.Write(34);
  MyFileWriter.Write('ABC');  // Chr(65) Chr(66) Chr(67)

  // Close the writer and the stream
  MyFileWriter.Close;
  MyFileStream.Close;

  // Reopen the stream for reading
  MyFileStream := System.IO.File.Open('C:DelphiBasics.txt',
                                      System.IO.FileMode.Open);

  // Create a BinaryReader to allow the file to be read back
  MyFileReader := System.IO.BinaryReader.Create(MyFileStream);

  // Declare our array to hold the returned data
  SetLength(MyByteArray, 7);

  // Get the whole file contents into the byte array
  MyByteArray := MyFileReader.ReadBytes(7);

  // Display our array contents
  for i := 0 to Length(MyByteArray)-1 do
    Console.WriteLine(MyByteArray[i].ToString);

  // Close the reader and the stream
  MyFileReader.Close;
  MyFileStream.Close;

  Console.Readline;
end.
   12
   34
   3
   65
   66
   67
 
 
Delphi Programming Neil Moffatt 2002 - 2017. All rights reserved.  |  Contact the author