Reading UDP data properly

[ankit.1g@gmail.com]

Hi all,

I am trying to read back the udp data , sent from my stepper motor. Reply varies from 3-12 bytes.

I am currently doing this to read my udp data:

qint64 size = udpSocket->pendingDatagramSize();
QHostAddress sender;
quint16 senderPort;
 char* reply = new char[size]
 qint64 res = udpSocket->readDatagram( reply, size, &sender, &senderPort );
 
char buf[12];
for ( int i = 2; i <= 11; ++i ) 
                buf[ i -2 ] = reply[ i ];
 
ui->Position->setText(buf);

qint64 size = udpSocket->pendingDatagramSize();
QHostAddress sender;
quint16 senderPort;
 char* reply = new char[size]
 qint64 res = udpSocket->readDatagram( reply, size, &sender, &senderPort );

char buf[12];
for ( int i = 2; i <= 11; ++i ) 
                buf[ i -2 ] = reply[ i ];

ui->Position->setText(buf);

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The problem I am facing is that sometime there are only 4 bytes sometime there are 11 bytes and when there are less bytes suppose 4-5 my text box will be filled with weird characters of unreadable format.
how can I change my current code to just read proper bytes received.