Visual FoxPro

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. Visual FoxPro

LOCAL lnSuccess
LOCAL loSock
LOCAL lnUseTls
LOCAL lnPort
LOCAL lnMaxWaitMs
LOCAL lnValue
LOCAL lnBigEndian
LOCAL lcHexStr

lnSuccess = 0

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

loSock = CreateObject('Chilkat.Socket')

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

lnUseTls = 0
lnPort = 4242
lnMaxWaitMs = 5000
lnSuccess = loSock.Connect("tcpbin.com",lnPort,lnUseTls,lnMaxWaitMs)
IF (lnSuccess = 0) THEN
    ? loSock.LastErrorText
    RELEASE loSock
    CANCEL
ENDIF

*  Wait a max of 2 seconds for a response..
loSock.MaxReadIdleMs = 2000

*  Send a 16-bit integer using big-endian byte ordering (also called network byte order)
*  12022 decimal = 2EF6 hex
lnValue = 12022
lnBigEndian = 1
loSock.SendInt16(lnValue,lnBigEndian)
*  Send it again, because we'll read it two different ways..
loSock.SendInt16(lnValue,lnBigEndian)

*  The tcpbin.com echo server only echoes after receiving an LF (linefeed char)
loSock.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.)
lcHexStr = loSock.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.
? "Expecting big-endian 2EF6"
? lcHexStr

*  Let's read directly to an integer..
lnSuccess = loSock.ReceiveInt16(lnBigEndian,1)
? "Expecting 12022"
? "Received: " + STR(loSock.ReceivedInt)

*  Consume the LF that gets echoed back..
loSock.ReceiveByte(1)

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

? "----"

*  12022 decimal = 2EF6 hex, but little-endian byte ordering will send the bytes in the order 0xF6 0x2E
lnValue = 12022
lnBigEndian = 0
loSock.SendInt16(lnValue,lnBigEndian)
loSock.SendInt16(lnValue,lnBigEndian)
loSock.SendByte(10)

lcHexStr = loSock.ReceiveNBytesENC(2,"hex")

? "Expecting little-endian F62E"
? lcHexStr

lnSuccess = loSock.ReceiveInt16(lnBigEndian,1)
? "Expecting 12022"
? "Received: " + STR(loSock.ReceivedInt)

*  Consume the LF that gets echoed back..
loSock.ReceiveByte(1)

loSock.Close(1000)

*  Output:

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

RELEASE loSock