EthernetNetIf TCP Socket connection problem

Questions » EthernetNetIf TCP Socket connection problem

10 years, 11 months ago.

in my programm i try to connect to a server with the TCPSocket class from the EthernetNetIf lib, but I just get the error that

"expression must have class type" in file "/HTTPServer.cpp", Line: 55, Col: 4

But what am I doing wrong I tried anything with const, pointers etc. I read the api carefully please help me to solve my problem.

Here is the code:

include the mbed library with this snippet

#include "mbed.h"
#include "EthernetNetIf.h"
#include "HTTPServer.h"
#include "RPCFunction.h"

/*
*   global Variables
*/
EthernetNetIf eth(
    IpAddr(192,168,1,22),
    IpAddr(255,255,255,0),
    IpAddr(192,168,0,1),
    IpAddr(192,168,0,1)
);
HTTPServer svr;
LocalFileSystem fs("webfs");
Serial pc(USBTX, USBRX);
TCPSocket *socket();
Host nodeServer();

/*
*   RPC functions
*/
void foo(char * input, char * output);
RPCFunction rpcFoo(&foo, "foo");

int main()
{
    /*
    *   Ethernet Inferface
    */
    printf("Setting up...\r\n");
    EthernetErr ethErr = eth.setup();
    if (ethErr) {
        printf("Error %d in setup.\r\n", ethErr);
        return -1;
    }
    printf("Setup OK\r\n");

    /*
    *   HTTP Server
    */
    FSHandler::mount("/webfs", "/"); //Mount /webfs path on web root path
    svr.addHandler<SimpleHandler>("/hello"); //Default handler
    svr.addHandler<RPCHandler>("/rpc");
    svr.addHandler<FSHandler>("/"); //Default handler
    svr.bind(80);
    printf("Listening...\r\n");

    /*
    *   TCP Socket
    */
    IpAddr nodeIp(192,168,1,22);
    Host node(nodeIp, 2222, "");
    socket.connect(&node);

    /*
    *   Endless loop
    */
    while (true) {
        Net::poll();
    }
}

/*
*   Functions
*/
void foo(char * input, char * output)
{
    pc.printf("foo\n");
}

3 Answers

10 years, 11 months ago.

I have never used the ethernet myself, however from a pure syntax perspective: Either line 55 must use a -> instead of a '.', Or on line 18 it must be declared without the '*'. (That last one probably).

Benjamin Richter

poster

10 years, 11 months ago.

Thank you but none of this was working. I also tried to import some other lib the EthernetInfterface library that is surely working but when i import it i just get errors. why is that?

Oleg Evsegneev

10 years, 8 months ago.

Hmm, I have got the same error in my fresh own class. Example:

DCM mydcm(void);
mydcm.doSome(); // raise error

But my old class works fine:

ESC esc(p21,p22,p23,p24);
esc.init(); // all is ok

Looks like an error in mbed compiler :(

I seriously doubt it is an error in the compiler. What it is is hard to tell without more info. Generally it happens when you use '.' to call a function while you have a pointer to a class. That isn't the case in your two lines, but surely there are more lines of relevant code.

posted by Erik - 07 Aug 2013

Are you sure that this isn't the case in those two lines which fail?

DCM mydcm(void);

That looks like it might be a prototype for a function which takes no parameters and returns an object of type DCM. I don't think is instantiating an object of type DCM.

posted by Adam Green 07 Aug 2013

I think, I have found the solution. When we write class contructor without arguments, like:

class MYC{
  public:
    int x;
    MYC(void);
};

MYC::MYC(void){
}

And then try to get some methods or properties from object:

#include "mbed.h"
#include "MYC.h"

MYC myc();

int main() {
    float x;
    x = myc.x;
}

so we get the error.

But, when we set some arguments in constructor, even unuseful:

class MYC{
  public:
    int x;
    MYC(int x);
};

MYC::MYC(int xx){
  x = xx;
}

#include "mbed.h"
#include "MYC.h"

MYC myc(1);

int main() {
    int x;
    x = myc.x;
}

All is ok

posted by Oleg Evsegneev 07 Aug 2013

For your first example:

MYC myc();

You do this instead:

MYC myc;

Just drop the parens.

posted by Adam Green 07 Aug 2013

Dont instantiate MYC with () , you are not forward declaring a function myc returning it MYC as type, do instead only MYC myc;

posted by H Soto 07 Aug 2013

I see. My fail :) thanks

posted by Oleg Evsegneev 07 Aug 2013

Benjamin Richter

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