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