udp - Why can't I receive text sent to localhost using UdpClient in C#? -


i trying write simple udp program in c# sends , receives data on localhost. beginner in c# better @ matlab instead of writing server , client in c#, decided send data using c# , receive in matlab.

i tried 2 approaches send data. using socket class worked, using udpclient class failed.

before running code, run matlab code set callback function print received datagram.

only 1 region active in each run. comment out other one.

using system; using system.collections.generic; using system.linq; using system.text; using system.net.sockets; using system.net;  namespace udp1 {     class program     {         const int port = 62745; //chosen @ random         static void main(string[] args)         {             string str = "hello world!";             byte[] sendbytes = encoding.ascii.getbytes(str);              #region 1 send data using socket class             socket sock = new socket(addressfamily.internetwork, sockettype.dgram, protocoltype.udp);             ipendpoint ipendpoint = new ipendpoint(ipaddress.parse("127.0.0.1"), port);             sock.sendto(sendbuff, ipendpoint);             console.readline();             #endregion              #region 2 send data using udpclient class             udpclient sendingclient = new udpclient(port);             sendingclient.send(sendbytes, sendbytes.length);             #endregion         }     } }

i getting

only 1 usage of each socket address (protocol/network address/port) permitted

error when run code in region 2.

however, when run code in region 1 works expect , receive data in matlab without problems.

here matlab code. have used code in other applications, highly doubt there wrong it. 

fclose(instrfindall); %close udp objects %udp configuration udpconfig.ipaddress = '127.0.0.1'; udpconfig.portaddress = 62745;  udpobj = udp(udpconfig.ipaddress, udpconfig.portaddress, ...     'localport',        udpconfig.portaddress, ...     'byteorder',        'bigendian');  set(udpobj, 'datagramterminatemode', 'on'); set(udpobj, 'datagramreceivedfcn', {@cbdatareceived, udpobj});  fopen(udpobj);

and callback function:

function cbdatareceived(hobj, eventdata, udpobj)     bytesavailable = get(udpobj, 'bytesavailable');     receiveddatagram = fread(udpobj, bytesavailable);     disp(char(receiveddatagram)); end

so, why getting error in udpclient case , not getting in socket case? there way avoid error?

i understand using same port both matlab , c# on same computer. thus, operating system not allow open same port different applications.

udp allows sending , receiving datagrams different ports, use different ports different applications if both applications running on same computer.

udpclient sendingclient = new udpclient(62746); // different port listen sendingclient.send(sendbytes, sendbytes.length, ipendpoint);

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