CkPython

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. CkPython

import sys
import chilkat

success = False

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

sock = chilkat.CkSocket()

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

useTls = False
port = 4242
maxWaitMs = 5000
success = sock.Connect("tcpbin.com",port,useTls,maxWaitMs)
if (success == False):
    print(sock.lastErrorText())
    sys.exit()

# Wait a max of 2 seconds for a response..
sock.put_MaxReadIdleMs(2000)

# Send a 16-bit integer using big-endian byte ordering (also called network byte order)
# 12022 decimal = 2EF6 hex
value = 12022
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.)
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..
success = sock.ReceiveInt16(bigEndian,True)
print("Expecting 12022")
print("Received: " + str(sock.get_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)

success = sock.ReceiveInt16(bigEndian,True)
print("Expecting 12022")
print("Received: " + str(sock.get_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