Dart

Socket Send/Receive 16-bit Integers

Demonstrates sending and receiving 16-bit integers over a socket connection using either big-endian or little-endian byte ordering. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final sock = CkSocket();

  // --------------------------------------------------------------------
  // This example uses the public TCP echo service at https://tcpbin.com/
  // --------------------------------------------------------------------

  final useTls = false;
  final port = 4242;
  final maxWaitMs = 5000;
  try {
    sock.connect('tcpbin.com', port, useTls, maxWaitMs);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Wait a max of 2 seconds for a response..
  sock.maxReadIdleMs = 2000;

  // Send a 16-bit integer using big-endian byte ordering (also called network byte order)
  // 12022 decimal = 2EF6 hex
  var value = 12022;
  var bigEndian = true;
  sock.sendInt16(value, bigEndian);
  // Send it again, because we'll read it two different ways..
  sock.sendInt16(value, bigEndian);

  // The tcpbin.com echo server only echoes after receiving an LF (linefeed char)
  sock.sendByte(10);

  // Let's see hex values of the 2 bytes sent in network byte order (big-endian)
  // (The echo server sends back exactly the bytes received.)
  var hexStr = sock.receiveNBytesENC(2, 'hex');

  // In the big-ending byte order, the byte order is most significant byte to least significant,
  // therefore we should see the bytes in the order 0x2E 0xF6.
  print('Expecting big-endian 2EF6');
  print(hexStr);

  // Let's read directly to an integer..
  sock.receiveInt16(bigEndian, true);
  print('Expecting 12022');
  print('Received: ${sock.receivedInt}');

  // Consume the LF that gets echoed back..
  sock.receiveByte(true);

  // --------------------------------------------------------------------
  // Let's do the same thing, but with little-endian byte ordering.

  print('----');

  // 12022 decimal = 2EF6 hex, but little-endian byte ordering will send the bytes in the order 0xF6 0x2E
  value = 12022;
  bigEndian = false;
  sock.sendInt16(value, bigEndian);
  sock.sendInt16(value, bigEndian);
  sock.sendByte(10);

  hexStr = sock.receiveNBytesENC(2, 'hex');

  print('Expecting little-endian F62E');
  print(hexStr);

  sock.receiveInt16(bigEndian, true);
  print('Expecting 12022');
  print('Received: ${sock.receivedInt}');

  // Consume the LF that gets echoed back..
  sock.receiveByte(true);

  sock.close(1000);

  // Output:

  // Expecting big-endian 2EF6
  // 2EF6
  // Expecting 12022
  // Received: 12022
  // ----
  // Expecting little-endian F62E
  // F62E
  // Expecting 12022
  // Received: 12022
}