undefined reference to `FIFORequestChannel::FIFORequestChannel - c++

Question

I am trying to copy data values from one .csv file to another, but when I am compiling I keep getting an undefined reference error. I am confused because I made sure to include the header file. Can anyone provide any input?
client.cpp (main):
#include "common.h"
#include "FIFOreqchannel.h" // this is where I included the header file
#include <iostream>
#include <string>
#include <stdio.h>
#include <sys/wait.h>
using namespace std;
int main(int argc, char *argv[]){
cout<<"test"<<endl;
int n = 100; // default number of requests per "patient"
int p = 15; // number of patients
srand(time_t(NULL));
struct timeval tv; // this is the starting struct
struct timeval ts;// this is the ending struct
gettimeofday(&tv, NULL); // starts the clock
FIFORequestChannel chan ("control", FIFORequestChannel::CLIENT_SIDE); // this is the creation of the server
//datamsg first = datamsg(1,59.996, 2); // This is the creation of the first datamsg. It gets the information for the first person, up to 59.996 seconds, and gets info from the second ecg.
//The next step is to create the file
string file = "x1.csv";
//gettimeofdayI(&start, null);
ofstream inputfile;
inputfile.open(file); // opens the data for the first person
double seconds = 0.0;
while (seconds<59.996){
datamsg ecg1 = datamsg(1,seconds,1); // gets the data from the first ECG
datamsg ecg2 = datamsg(1,seconds,2); // gets the data from the second ECG
//cout<<test<<endl;
char*size= new char [sizeof(ecg1)];
*(datamsg*)size=ecg1;
chan.cwrite(size,sizeof(ecg1));
char * read=chan.cread();
double ecgfirst=*(double*)read;
inputfile<<ecgfirst<<","<<"\n";
char*size2= new char [sizeof(ecg2)];
*(datamsg*)size2=ecg2;
chan.cwrite(size2,sizeof(ecg2));
char * read2=chan.cread();
double ecgsecond=*(double*)read2;
inputfile<<ecgsecond<<","<<"\n";
seconds = seconds +.004; // this is the incrementation of the seconds
}
inputfile.close();
gettimeofday(&ts, NULL);
double totaltime; // this will count the total time of the process
totaltime = ts.tv_sec-tv.tv_sec;
cout<<" The total time to get the info for person is "<<totaltime<<"."<<endl;
// sending a non-sense message, you need to change this
char x = 55;
chan.cwrite (&x, sizeof (x));
char* buf = chan.cread ();
// closing the channel
MESSAGE_TYPE m = QUIT_MSG;
chan.cwrite (&m, sizeof (MESSAGE_TYPE));
}
FIFOreqchannel.h:
#ifndef _FIFOreqchannel_H_
#define _FIFOreqchannel_H_
#include "common.h"
class FIFORequestChannel
{
public:
enum Side {SERVER_SIDE, CLIENT_SIDE};
enum Mode {READ_MODE, WRITE_MODE};
private:
/* The current implementation uses named pipes. */
string my_name;
Side my_side;
int wfd;
int rfd;
string pipe1, pipe2;
int open_pipe(string _pipe_name, int mode);
public:
FIFORequestChannel(const string _name, const Side _side);
/* Creates a "local copy" of the channel specified by the given name.
If the channel does not exist, the associated IPC mechanisms are
created. If the channel exists already, this object is associated with the channel.
The channel has two ends, which are conveniently called "SERVER_SIDE" and "CLIENT_SIDE".
If two processes connect through a channel, one has to connect on the server side
and the other on the client side. Otherwise the results are unpredictable.
NOTE: If the creation of the request channel fails (typically happens when too many
request channels are being created) and error message is displayed, and the program
unceremoniously exits.
NOTE: It is easy to open too many request channels in parallel. Most systems
limit the number of open files per process.
*/
~FIFORequestChannel();
/* Destructor of the local copy of the bus. By default, the Server Side deletes any IPC
mechanisms associated with the channel. */
char* cread(int *len=NULL);
/* Blocking read of data from the channel. Returns a string of characters
read from the channel. Returns NULL if read failed. */
int cwrite(void *msg, int msglen);
/* Write the data to the channel. The function returns the number of characters written
to the channel. */
string name();
};
#endif
FIFOreqchannel.cpp:
#include "common.h"
#include "FIFOreqchannel.h"
using namespace std;
/*--------------------------------------------------------------------------
*/
/* CONSTRUCTOR/DESTRUCTOR FOR CLASS R e q u e s t C h a n n e l */
/*--------------------------------------------------------------------------
*/
FIFORequestChannel::FIFORequestChannel(const string _name, const Side _side)
: my_name( _name), my_side(_side){
pipe1 = "fifo_" + my_name + "1";
pipe2 = "fifo_" + my_name + "2";
if (_side == SERVER_SIDE){
wfd = open_pipe(pipe1, O_WRONLY);
rfd = open_pipe(pipe2, O_RDONLY);
}
else{
rfd = open_pipe(pipe1, O_RDONLY);
wfd = open_pipe(pipe2, O_WRONLY);
}
}
FIFORequestChannel::~FIFORequestChannel(){
close(wfd);
close(rfd);
remove(pipe1.c_str());
remove(pipe2.c_str());
}
int FIFORequestChannel::open_pipe(string _pipe_name, int mode){
mkfifo (_pipe_name.c_str (), 0600);
int fd = open(_pipe_name.c_str(), mode);
if (fd < 0){
EXITONERROR(_pipe_name);
}
return fd;
}
char* FIFORequestChannel::cread(int *len){
char * buf = new char [MAX_MESSAGE];
int length = read(rfd, buf, MAX_MESSAGE);
if (length < 0){
EXITONERROR ("Connection Error");
}
if (len) // the caller wants to know the length
*len = length;
return buf;
}
int FIFORequestChannel::cwrite(void* msg, int len){
if (len > MAX_MESSAGE){
cerr << "message length exceeds buffer size" << endl;
exit (-1);
}
if (write(wfd, msg, len) < 0){
EXITONERROR("cwrite");
}
return len;
}
The errors I am getting are undefined reference errors. So, I assume that it is a problem with linking, but I am confused because I included the header file.
Here are the errors I am getting:
client.cpp:(.text+0xc8): undefined reference to
`FIFORequestChannel::FIFORequestChannel(std::__cxx11::basic_string<char, std::char_traits<char>,
std::allocator<char> >, FIFORequestChannel::Side)'
client.cpp:(.text+0x22e): undefined reference to `FIFORequestChannel::cwrite(void*, int)'
client.cpp:(.text+0x242): undefined reference to `FIFORequestChannel::cread(int*)'
client.cpp:(.text+0x2f3): undefined reference to `FIFORequestChannel::cwrite(void*, int)'
client.cpp:(.text+0x307): undefined reference to `FIFORequestChannel::cread(int*)'
client.cpp:(.text+0x446): undefined reference to `FIFORequestChannel::cwrite(void*, int)'
client.cpp:(.text+0x45a): undefined reference to `FIFORequestChannel::cread(int*)'
client.cpp:(.text+0x489): undefined reference to `FIFORequestChannel::cwrite(void*, int)'
client.cpp:(.text+0x4b6): undefined reference to `FIFORequestChannel::~FIFORequestChannel()'
client.cpp:(.text+0x54d): undefined reference to `FIFORequestChannel::~FIFORequestChannel()'
collect2: error: ld returned 1 exit status
I am using Cloud 9 IDE on Amazon Webservices, and all the files are in the same folder.

Answer 1

I am confused because I made sure to include the header file.
Using #include "FIFOreqchannel.h" is necessary, but not sufficient to link your program. You must also supply FIFOreqchannel.o to the linker.
You are doing something like:
g++ client.cpp
You should do:
g++ client.cpp FIFOreqchannel.cpp ...other_object_files... ...other_libraries...