Lua

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. Lua

local chilkat = require("chilkat")

-- This example requires the Chilkat API to have been previously unlocked.
-- See Global Unlock Sample for sample code.

local sock = chilkat.Socket.new()

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

local useTls = false
local port = 4242
local maxWaitMs = 5000
local success = sock:connect("tcpbin.com", port, useTls, maxWaitMs)
if not success then
    print(sock.last_error_text)
    return
end

-- Wait a max of 2 seconds for a response..
sock.max_read_idle_ms = 2000

-- Send a 16-bit integer using big-endian byte ordering (also called network byte order)
-- 12022 decimal = 2EF6 hex
local value = 12022
local bigEndian = true
sock:send_int16(value, bigEndian)
-- Send it again, because we'll read it two different ways..
sock:send_int16(value, bigEndian)

-- The tcpbin.com echo server only echoes after receiving an LF (linefeed char)
sock:send_byte(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.)
local hexStr = sock:receive_n_bytes_enc(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..
success = sock:receive_int16(bigEndian, true)
print("Expecting 12022")
print("Received: " .. sock.received_int)

-- Consume the LF that gets echoed back..
sock:receive_byte(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:send_int16(value, bigEndian)
sock:send_int16(value, bigEndian)
sock:send_byte(10)

hexStr = sock:receive_n_bytes_enc(2, "hex")

print("Expecting little-endian F62E")
print(hexStr)

success = sock:receive_int16(bigEndian, true)
print("Expecting 12022")
print("Received: " .. sock.received_int)

-- Consume the LF that gets echoed back..
sock:receive_byte(true)

sock:close(1000)

-- Output:

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