Object initialize

[satyanarayana143]

Hi friends,

I am trying to initialize array of class object to null i am getting error.
variable sized object cannot be initialized how can i check .

channelinfoobj *m_nchannelinfoobj[4] == NULL;

cananybody tell how to initialize.

[jsulm]

@satyanarayana143 said in Object initialize:

channelinfoobj *m_nchannelinfoobj[4] == NULL;

This is not an assignment.
And you can't just assign nullptr to an array as it has several elements.

channelinfoobj *m_nchannelinfoobj[4] { nullptr, nullptr, nullptr, nullptr };

[satyanarayana143]

@jsulm said in Object initialize:

4

channelinfoobj *m_nchannelinfoobj[4] { nullptr, nullptr, nullptr, nullptr };

i can give like this but 4 value i t will come dynamically for understanding i have given 4. it will come channelcnt.

[jsulm]

@satyanarayana143 said in Object initialize:

i can give like this but 4 value i t will come dynamically for understanding i have given 4. it will come channelcnt.

You can always use a loop to initialise the elements:

channelinfoobj *m_nchannelinfoobj[4];
for (int i = 0; i < 4; ++i)
    m_nchannelinfoobj[i] = nullptr;

[satyanarayana143]

channelinfoobj *m_nchannelinfoobj[4];
for (int i = 0; i < 4; ++i)
{
m_nchannelinfoobj[i] = nullptr;
m_nchannelinfoobj[i] = new channelinfoobj ();
}

this loop function will call every 5 sec then i have to validate new is already created or not . m_nchannelinfoobj[i] = nullptr; every time it will be null.
m_nchannelinfoobj[i] using by other .

[jsulm]

@satyanarayana143 said in Object initialize:

every time it will be null

No, because you're assigning it a valid pointer just after assigning nullptr (I have no idea why you're doing this!), so it will be always != nullptr (unless you assign nullptr somewhere else):

for (int i = 0; i < 4; ++i)
{
    m_nchannelinfoobj[i] = nullptr; // Why?! Next line you're assigning a pointer to it.
    m_nchannelinfoobj[i] = new channelinfoobj (); // Now it is not nullptr any-more
}

"then i have to validate new is already created or not " - isn't that as simple as:

if (m_nchannelinfoobj[i]) {
    // Do something
}

?

Can you please explain better what you want to achieve and what the problem is?

[satyanarayana143]

void EdgeClient::processPendingDatagrams()
{
struct uftp_h *header;
int packetlen = 0;

header = (struct uftp_h *)malloc(sizeof(struct uftp_h));

struct ChannelInfo_Recieve* channelData;

QByteArray datagram;
datagram.resize(udpSocket->pendingDatagramSize());
udpSocket->readDatagram(datagram.data(),datagram.size());

unsigned char *pCmdBuffer = (unsigned char*)datagram.data();

memcpy(header,pCmdBuffer,sizeof(struct uftp_h));
packetlen+= sizeof(struct uftp_h);

qDebug() <<  "Socket Read Bytes:" << datagram.size() << "####### Header Info  #########" << "Vernum:" << header->version
          << "Announce:" << header->func <<"channel Count:" << header->channelcnt ;

channelInfoStruct *m_nchannelInfoStruct[header->channelcnt];

for(int i = 0;i < header->channelcnt;i++)
{
    m_nchannelInfoStruct[i] = new channelInfoStruct();
    channelData = (struct ChannelInfo_Recieve *)malloc(sizeof(struct ChannelInfo_Recieve));
    uint16_t *pgrp = (uint16_t *)malloc(channelData->groupsize*sizeof(uint16_t));

    if(packetlen+sizeof(struct ChannelInfo_Recieve) > MAX_BUFFERSIZE)
    {
        qDebug() << "######### Receive Buffer size Exceeded ##############";
        exit(0);
    }

    memcpy(channelData,pCmdBuffer+packetlen,sizeof(struct ChannelInfo_Recieve));
    packetlen+= sizeof(struct ChannelInfo_Recieve);

    struct in_addr Inaddr = {channelData->InputIPAddress};
    struct in_addr outaddr = {channelData->outputIPAddress};

    qDebug() << "######################################################";

    qDebug() <<"ChannelType:" << channelData->channelType << "OutputPort:" << channelData->OutputPort
            <<"Inputport:" << channelData->Inputport  << "GroupSize:" << channelData->groupsize
           <<"InputIPAddress:"<<inet_ntoa(Inaddr)<< "outputIPAddress:"<<inet_ntoa(outaddr) << endl;


    qDebug() << "OutputPort:" << channelData->OutputPort;

    if(packetlen+(channelData->groupsize*sizeof(uint16_t)) > MAX_BUFFERSIZE)
    {
        qDebug() << "######### Receive Buffer size Exceeded ##############";
        exit(0);
    }

    memcpy(pgrp,pCmdBuffer+packetlen,channelData->groupsize*sizeof(uint16_t));
    packetlen+= channelData->groupsize*sizeof(uint16_t);


    //        for(int gid = 0;gid < schData->groupsize;gid++)
    //        {
    //            qDebug() << "sGroupID:" << pgrp[gid];
    //        }

    QString m_SystemIp ;
    struct ifaddrs *ifaddr, *ifa;
    int family, s;
    char host[NI_MAXHOST];

    if (getifaddrs(&ifaddr) == -1)
    {
        perror("getifaddrs");
        exit(EXIT_FAILURE);
    }
    for (ifa = ifaddr; ifa != nullptr; ifa = ifa->ifa_next)
    {
        if (ifa->ifa_addr == nullptr)
            continue;

        s = getnameinfo(ifa->ifa_addr,sizeof(struct sockaddr_in),host, NI_MAXHOST, nullptr,0, NI_NUMERICHOST);

        if( ((strcmp(ifa->ifa_name,"wlan0")==0)&&(ifa->ifa_addr->sa_family==AF_INET)) ||  ((strcmp(ifa->ifa_name,"enp3s0")==0)&&(ifa->ifa_addr->sa_family==AF_INET))
                || ((strcmp(ifa->ifa_name,"eth0")==0)&&(ifa->ifa_addr->sa_family==AF_INET)))
        {
            if (s != 0)
            {
                qDebug("getnameinfo() failed: %s\n", gai_strerror(s));
                exit(EXIT_FAILURE);
            }
            qDebug("Interface : %s ",ifa->ifa_name );
            qDebug("Address : %s", host);

            m_SystemIp = host;
            qDebug() << "m_SystemIp:" << m_SystemIp;
        }
    }

    freeifaddrs(ifaddr);


    if(channelData->channelType == FILETYPE)
    {

        if(m_nchannelInfoStruct[i]->FilePublicIp == inet_ntoa(Inaddr) && m_nchannelInfoStruct[i]->FileOutputport == channelData->OutputPort)
        {
            qDebug() << "########## File MultiCast IpAddress and port Used i ############";
        }
        else
        {
            qDebug() << "########## File MultiCast IpAddress and Port not Used i ############";

            //Store File PublicMulticast IP and Port
            if (m_nchannelInfoStruct[i]->m_nchannelProcess.state() == QProcess::NotRunning)
            {
                m_nchannelInfoStruct[i]->FilePublicIp  = inet_ntoa(Inaddr);
                m_nchannelInfoStruct[i]->FileOutputport = channelData->OutputPort;

                qDebug().noquote() << "############ File Process not Running i ##############" << i << "FileOutputport:"
                                   << m_nchannelInfoStruct[i]->FileOutputport << "FilePublicIp:" << m_nchannelInfoStruct[i]->FilePublicIp;

                QString program = qApp->applicationDirPath()+"/uftpd";


                QStringList arguments;
                arguments << "-M"<< m_nchannelInfoStruct[i]->FilePublicIp << "-p" << QString::number(m_nchannelInfoStruct[i]->FileOutputport) << "-D" << RECEIVE_FILE_PATH;
                qDebug() <<"File Program:"<< program <<"File arguments:" << arguments;
                m_nchannelInfoStruct[i]->m_nchannelProcess.start(program,arguments);
            }
            else
            {
                qDebug().noquote() << "############ File Process Already Running i ##############";
            }

        }
    }
    else if(channelData->channelType == LIVESTREAMTYPE)
    {
        if (m_nchannelInfoStruct[i]->m_nchannelProcess.state() == QProcess::NotRunning)
        {
            qDebug().noquote() << "############ OnStream Process not Running j ##############";
            if(m_nchannelInfoStruct[i]->onStreamIP == inet_ntoa(outaddr) && m_nchannelInfoStruct[i]->onStreamport ==  channelData->OutputPort)
            {
                qDebug() << "############## Stream Ip and Port Already Used ###############";
            }
            else
            {
                m_nchannelInfoStruct[i]->onStreamIP   = inet_ntoa(outaddr);
                m_nchannelInfoStruct[i]->onStreamport =  channelData->OutputPort;
            }
            QString Streamfeed = "feed"+QString::number(i+1);
            QStringList  argumentsList ;
            if(m_nchannelInfoStruct[i]->onStreamIP >= "224.0.0.0 " && m_nchannelInfoStruct[i]->onStreamIP <= "239.255.255.255")
            {
                argumentsList << m_nchannelInfoStruct[i]->onStreamIP << QString::number(m_nchannelInfoStruct[i]->onStreamport)
                              << Streamfeed;
            }
            else
            {
                argumentsList << m_nchannelInfoStruct[i]->onStreamIP << QString::number(m_nchannelInfoStruct[i]->onStreamport)
                              << Streamfeed;
            }

            QString program = qApp->applicationDirPath()+"/StreamTest.sh";
            qDebug() <<"Porcess and Arguments" <<  program << argumentsList;
            m_nchannelInfoStruct[i]->m_nchannelProcess.start(program,argumentsList);
        }
    }
    else
    {
        qDebug() << "########### Invalid Channel Type ############";
    }

}

}

this function will call every 5 sec once

m_nchannelInfoStruct[i]->m_nchannelProcess.start() it will be running state if c create new it will be destroyed what is running in process.

[jsulm]

@satyanarayana143 said in Object initialize:

datagram.resize(udpSocket->pendingDatagramSize());

What is the problem? I don't have time to analyse all this code, please be so kind and tell what the problem is, or which specific part of the code you mean.

Just a note: you're writing quite low-level code (C style, memcpy, malloc), shouldn't be necessary with Qt/C++.

[satyanarayana143]

channelInfoStruct *m_nchannelInfoStruct[header->channelcnt];

for(int i = 0;i < header->channelcnt;i++)
{
m_nchannelInfoStruct[i] = new channelInfoStruct();
}

[jsulm]

@satyanarayana143 ?

[satyanarayana143]

channelInfoStruct *m_nchannelInfoStruct[header->channelcnt];

for(int i = 0;i < header->channelcnt;i++)
{
m_nchannelInfoStruct[i] = new channelInfoStruct();
}
m_nchannelInfoStruct[i] i am starting process it is in running mode foe every 5 sec i am calling this function new of m_nchannelInfoStruct[i] is creating when i create new if process is running i am getting Qprocess destroyed i want to check
if m_nchannelInfoStruct[i] = new channelInfoStruct(); already created i dont want to create new again.

[jsulm]

@satyanarayana143 said in Object initialize:

if m_nchannelInfoStruct[i] = new channelInfoStruct(); already created i dont want to create new again.

I already provided code for that, did you read it?
Here once more:

if (m_nchannelinfoobj[i]) {
    // Do something
}

So, in your case:

if (!m_nchannelinfoobj[i]) {
    m_nchannelInfoStruct[i] = new channelInfoStruct();
}

[satyanarayana143]

if (!m_nchannelinfoobj[i]) {
m_nchannelInfoStruct[i] = new channelInfoStruct();
}

when i create like this and starting QProcess it is crashing

[jsulm]

@satyanarayana143 said in Object initialize:

when i create like this and starting QProcess it is crashing

Then use debugger to see what happens...
Also, if you delete m_nchannelInfoStruct[i] you need to set it to nullptr:

delete m_nchannelInfoStruct[i];
m_nchannelInfoStruct[i] = nullptr;

And: m_nchannelInfoStruct is a local variable, so it goes out of scope and is destroyed as soon as it leaves its scope...
m_ prefix is usually used to mark member variables but m_nchannelInfoStruct is a local variable in your code...

[satyanarayana143]

delete m_nchannelInfoStruct[i];
m_nchannelInfoStruct[i] = nullptr;

i am not calling delete

[JonB]

@satyanarayana143
As @jsulm is telling you:

void EdgeClient::processPendingDatagrams()
{
    channelInfoStruct *m_nchannelInfoStruct[header->channelcnt];

    for(int i = 0;i < header->channelcnt;i++)
    {
          m_nchannelInfoStruct[i] = new channelInfoStruct(); 
          m_nchannelInfoStruct[i]->m_nchannelProcess.start(program,argumentsList);
    }

    // m_nchannelInfoStruct destroyed here
}

m_nchannelInfoStruct is a local variable in processPendingDatagrams() function. When that exits the array is destroyed.

Then your m_nchannelProcess, you are starting a new process, on the same QProcess variable, each time round. Dunno what's going on there.