error: cannot convert 'CPacket' to 'CPacket*'

[Msung]

Hi, I've just joined the forum because I've found the tutorials on this website really useful and I've kinda come into a problem with a program I've made in C++ and am hoping for some help.

The title is the error message I get from the compiler.
I've put some of the code below.

Its meant to be used to generate data for a Network Simulator and all i need to do is ask a user to input data and then ask if they want to store to a file. But obviously this data needs to be validated so this is where the problem occurs....

At the beginning of the program I made an array of the class CPacket which is the end result of where I want to store my data. I also have another class called temp_CPacket which stores the values in temporarily allowing me to validate them. Since this is a temp storage place, I only initialize the 1 class.

The variable nPackets is a global variable which I use to keep track of which "number" CPacket I'm in within the array. I made it global so that it can be tracked throughout the entire program. I had made this a Class variable before hand but then I ran into this problem and I though that making it a global variable would fix it....it didn't, and I just left it as a global because it was easier really.

int main()
{
    int selection=NULL, /*nPackets=1,*/ *ptr_nPackets; 
//stores the users choice in the menu
    nPackets--; 
//gets rid of the initial packet created due to initialisation
    ptr_nPackets = &nPackets;
    char memoryFlush = NULL, another_packet=NULL; 
//stores whether the packets have been removed from memory (either by file write or discard)
    string dat, buffer; 
//stores the data value temporarily and stores the input from user for the data packets
    CPacket packet[packet_max];
    temp_CPacket temp_packet;

    while(true)
    {

The problem occurs when I try to pass forward the array of class CPacket into the function create_packet( ) which I need to put the global varible nPacket (the ptr_nPackets was another attempt to get around this problem but again this failed) but then I get the error code in the title....

cout << "Do you wish to create another packet? (Y/N)\n: ";
                    cin >> another_packet;
                    while (true)
                    {
                        if(make_another_packet(another_packet)==1)
                        {
                            break;
                        }
                        else
                        {
                            create_packet(temp_packet, packet[nPackets] /*ptr_nPackets*/ ); //error
                            break;                            
                        }
                    }

//........................ //skip to create_packet, I presume the error is at the bottom of this

void create_packet(temp_CPacket temp, CPacket packet[] /*int* ptr_nPackets*/ )
{
    cout << "\nSource Address (1-1024): ";
    cin.ignore(255,'\n');
    getline(cin, temp.buffer);

    temp.src = validate_string(temp.buffer, temp.src);
    while((temp.src > 1024 || temp.src < 1))
    {
        cout << "\nInvalid data entry, please re-enter: ";
        getline(cin, temp.buffer);
        temp.src = validate_string(temp.buffer, temp.src);
    }

    cout << "\nDestination Address (1-1024): ";
    getline(cin, temp.buffer);
    cin.ignore(255,'\n');
    temp.dst = validate_string(temp.buffer, temp.dst);
    while((temp.dst > 1024 || temp.dst < 1))
    {
        cout << "\nInvalid data entry, please re-enter: ";
        getline(cin, temp.buffer);
        temp.dst = validate_string(temp.buffer, temp.dst);
    }

    cout << "\nType (0-10): ";
    getline(cin, temp.buffer);
    cin.ignore(255,'\n');
    temp.typ = validate_string(temp.buffer, temp.typ);
    while((temp.typ > 10 || temp.typ < 0))
    {
        cout << "\nInvalid data entry, please re-enter: ";
        getline(cin, temp.buffer);
        temp.typ = validate_string(temp.buffer, temp.typ);
    }

    cout << "\nPort (1-1024): ";
    getline(cin, temp.buffer);
    cin.ignore(255,'\n');
    temp.prt = validate_string(temp.buffer, temp.prt);
    while((temp.prt > 1024 || temp.prt < 1))
    {
        cout << "\nInvalid data entry, please re-enter: ";
        getline(cin, temp.buffer);
        temp.prt = validate_string(temp.buffer, temp.prt);
    }

    cout << "\nData (50 chars max): ";
    getline(cin, temp.dat);
    while (validate_dataString(temp.dat)==false)
    {
        cout << "\nInvalid data entry, please re-enter: ";
        getline(cin, temp.dat);
        cin.ignore(255,'\n');
    }

    cout << "\nPacket " << nPackets << " created.";
    nPackets++;
    packet[nPackets].set_values(temp); //possibly the location of error?

}

So that's my problem, sorry if I'm not making much sense, I have no idea what the hell is happening with it and its really frustrating me because I think its actually quite a simple problem to do with the relationship between arrays and pointers but I have no idea what.... If you want to see the full code, just say and I'll post it.

Thanks if you can help!

[vlad from moscow]

The error message is very clear. So I do not see any problem. Your function create_packet

void create_packet(temp_CPacket temp, CPacket packet[] /*int* ptr_nPackets*/ )

is defined such a way that its second parameter is a pointer to CPacket, that is CPacket *. But you are trying to pass it object of the type CPacket

create_packet(temp_packet, packet[nPackets] /*ptr_nPackets*/ );

because packet[nPackets] denotes the alement of the array that corresponds to the index nPackets

[Msung]

Oh right! That's make sense. Well how would i implement it how i wanted to? Because i cant imagine how to get it to do it any other way other than how I did it....probably why i did like that I suppose...

Also, thanks for the reply, gives me a better insight as to why, I was really confused as to why it was telling me that my second parameter was a pointer to CPacket, i presume its to do with the fact that it's an array?


EDIT:
I understand that its telling me its a pointer to CPacket, this is I'm assuming to do with the fact that arrays are just pointers to the beginning of a list of memory locations. But I just dont understand what I could do to get around this problem....
It's kinda the only thing that's stopping me from finishing this program as well, granted my code writing is a mess but I can look over that without stressing too much.

[clanmjc]

create_packet(temp_packet, packet[nPackets] /*ptr_nPackets*/ ); //error
This is the code version of vlad's exact words.
create_packet(temp_packet, packet /*ptr_nPackets*/ ); //error

[Vlykarye]

Try this:

create_packet(temp_packet, packet + nPackets);

If packet is the pointer to the beginning of your array, packet + nPackets should be the pointer to the beginning + nPackets.

[Msung]

Yes! That's made it work! Thank you so much for the help! I can't believe it was something so simple to get it this to finally work!

Got it all up and running now! ..... and then I realise I need to remove all my ptr_nPackets and stuff. Oh well, that's minor issues compared to the create_packet one. Once again, thank you everybody for helping!