Reads a block of data records from an untyped binary file System unit
 procedure BlockRead(var FileHandle File; var Buffer; RecordCount Integer {; var RecordsRead Integer});
The BlockRead procedure is used to read RecordCount data records into Buffer from an untyped binary file given by the FileHandle.
The file must have been assigned using AssignFile and opened with Reset.
The Reset routine by default will open the file with a record size of 128 bytes. This can be overriden in this routine to a value more useful to yourself (see example).
Data is written to the Buffer (normally a string or byte array) from the file. If the recordSize is 10 bytes, and RecordCount is 3, then 3 x 10 byte records are written, with 30 bytes taken from the file to do this.
The actual number of records read is stored in the optional RecordsRead variable, if provided. It will be less than RecordCount if, for example, the end of the file has been reached.
Related commands
BlockWriteWrites a block of data records to an untyped binary file
FileDefines a typed or untyped file
ReadRead data from a binary or text file
ReadLnRead a complete line of data from a text file
ResetOpen a text file for reading, or binary file for read/write
WriteWrite data to a binary or text file
WriteLnWrite a complete line of data to a text file
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Example code : Reading data from a binary file one byte at a time.
  myFile    : File;
  byteArray : array[1..8] of byte;
  oneByte   : byte;
  i, count  : Integer;

  // Try to open the Test.byt file for writing to
  AssignFile(myFile, 'Test.byt');
  ReWrite(myFile, 4);  // Define a single 'record' as 4 bytes

  // Fill out the data array
  for i := 1 to 8 do
    byteArray[i] := i;

  // Write the data array to the file
  BlockWrite(myFile, byteArray, 2);  // Write 2 'records' of 4 bytes

  // Close the file

  // Reopen the file for reading
  FileMode := fmOpenRead;
  Reset(myFile, 1);  // Now we define one record as 1 byte

  // Display the file contents
  // Start with a read of the first 6 bytes. 'count' is set to the
  // actual number read
  ShowMessage('Reading first set of bytes :');
  BlockRead(myFile, byteArray, 6, count);

  // Display the byte values read
  for i := 1 to count do

  // Now read one byte at a time to the end of the file
  ShowMessage('Reading remaining bytes :');
  while not Eof(myFile) do
    BlockRead(myFile, oneByte, 1);  // Read one byte at a time

  // Close the file for the last time
Show full unit code
  Reading first set of bytes :
  Reading remaining bytes :
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