QtcpSocket read behavior

[grisson]

Hi.
I'm trying to understand the read behavior of QTcpSocket::read(maxSize) function.
i have the following code (on the server):

#include "server.h"
#include <QTcpSocket>
#include <iostream>
server::server()
{
    s=new QTcpServer;
 
}
void server::active(){
    s->listen(QHostAddress::Any,5500);
    connect(s,SIGNAL(newConnection()),this,SLOT(nc()));
}
void server::nc(){
 
    QTcpSocket *so=s->nextPendingConnection();
 
    while(true){
        std::cout <<"wait read..."<<std::endl;
        so->waitForReadyRead(5000000);
        QByteArray a=so->read(1000);
        if (a.endsWith("\r\n"))
                a.resize(a.length()-2);
        if (a.startsWith("quit"))
            break;
 
       //just to see readed text, this line will be deleted
        std::cout <<a.length()<<"--"<<QString(a).toStdString()<<std::endl;
    }
    so->disconnectFromHost();
}

#include "server.h"
#include <QTcpSocket>
#include <iostream>
server::server()
{
    s=new QTcpServer;

}
void server::active(){
    s->listen(QHostAddress::Any,5500);
    connect(s,SIGNAL(newConnection()),this,SLOT(nc()));
}
void server::nc(){

    QTcpSocket *so=s->nextPendingConnection();

    while(true){
        std::cout <<"wait read..."<<std::endl;
        so->waitForReadyRead(5000000);
        QByteArray a=so->read(1000);
        if (a.endsWith("\r\n"))
                a.resize(a.length()-2);
        if (a.startsWith("quit"))
            break;

       //just to see readed text, this line will be deleted
        std::cout <<a.length()<<"--"<<QString(a).toStdString()<<std::endl;
    }
    so->disconnectFromHost();
}

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and for testing, i use putty to connect in raw mode to the server.
So, if i send with putty these lines:

testline1

testline1

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the server will output this

wait read...
9--testline1
wait read...
0--
wait read...

wait read...
9--testline1
wait read...
0--
wait read...

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analizing the behavior, line 1,2 and 3 are ok, but line 4 is unexpected(or not?)... if i input other lines like:

testline1
testline222222
 
lastwasempty

testline1
testline222222

lastwasempty

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note that line 3 is empty

the server output is:

wait read...
9--testline1
wait read...
0--
wait read...
14--testline222222
wait read...
0--
wait read...
0--
wait read...
12--lastwasempty
wait read...
0--
wait read...

wait read...
9--testline1
wait read...
0--
wait read...
14--testline222222
wait read...
0--
wait read...
0--
wait read...
12--lastwasempty
wait read...
0--
wait read...

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like previois example example, i can't understand why lines 4,8 and 14 are present...(obviously same thing for the "wait read" related lines, but this is not important)
some explanations?