What is the easiest way to resolve c++ linking error

Question

I have multiple c++ class files and header files when i attempt to compile them i get the following error.I even tried using cmake to make my life easier but i still get it:

make: Warning: File `Makefile' has modification time 11 s in the future
make[1]: Warning: File `CMakeFiles/Makefile2' has modification time 11 s in the future
make[2]: Warning: File `src/CMakeFiles/simulation.dir/flags.make' has modification time 11 s in the future
Scanning dependencies of target simulation
make[2]: warning:  Clock skew detected.  Your build may be incomplete.
make[2]: Warning: File `src/CMakeFiles/simulation.dir/flags.make' has modification time 11 s in the future
[  4%] Building CXX object src/CMakeFiles/simulation.dir/OS.cxx.o
[  9%] Building CXX object src/CMakeFiles/simulation.dir/Ram.cxx.o
[ 14%] Building CXX object src/CMakeFiles/simulation.dir/RamQueues.cxx.o
[ 19%] Building CXX object src/CMakeFiles/simulation.dir/HardDisk.cxx.o
[ 23%] Building CXX object src/CMakeFiles/simulation.dir/CpuRegisters.cxx.o
[ 28%] Building CXX object src/CMakeFiles/simulation.dir/BankersAlgorithm.cxx.o
[ 33%] Building CXX object src/CMakeFiles/simulation.dir/Clock.cxx.o
[ 38%] Building CXX object src/CMakeFiles/simulation.dir/random.cxx.o
[ 42%] Building CXX object src/CMakeFiles/simulation.dir/PCB.cxx.o
[ 47%] Building CXX object src/CMakeFiles/simulation.dir/File.cxx.o
[ 52%] Building CXX object src/CMakeFiles/simulation.dir/Jobs.cxx.o
[ 57%] Building CXX object src/CMakeFiles/simulation.dir/Cpu.cxx.o
[ 61%] Building CXX object src/CMakeFiles/simulation.dir/JobCreationFactory.cxx.o
[ 66%] Building CXX object src/CMakeFiles/simulation.dir/StateQueue.cxx.o
[ 71%] Building CXX object src/CMakeFiles/simulation.dir/Keyboard.cxx.o
[ 76%] Building CXX object src/CMakeFiles/simulation.dir/Mouse.cxx.o
[ 80%] Building CXX object src/CMakeFiles/simulation.dir/Monitor.cxx.o
[ 85%] Building CXX object src/CMakeFiles/simulation.dir/ReadyQueue.cxx.o
[ 90%] Building CXX object src/CMakeFiles/simulation.dir/TerminatingQueue.cxx.o
[ 95%] Building CXX object src/CMakeFiles/simulation.dir/WaitingQueue.cxx.o
[100%] Building CXX object src/CMakeFiles/simulation.dir/osTester.cxx.o
Linking CXX executable simulation
CMakeFiles/simulation.dir/osTester.cxx.o: In function `main':
osTester.cxx:(.text+0xa3): undefined reference to `JobCreationFactory::createFiles(HardDisk)'
osTester.cxx:(.text+0xb9): undefined reference to `JobCreationFactory::createJobs(HardDisk)'
osTester.cxx:(.text+0xee): undefined reference to `HardDisk::setNumberOfJobs(int)'
osTester.cxx:(.text+0x2fe): undefined reference to `OS::setSchedulingAlgorithm(int)'
osTester.cxx:(.text+0x32c): undefined reference to `OS::osTakeOver(HardDisk, Ram, Cpu, Mouse, Monitor, Keyboard)'
collect2: ld returned 1 exit status
make[2]: *** [src/simulation] Error 1
make[1]: *** [src/CMakeFiles/simulation.dir/all] Error 2
make: *** [all] Error 2

how can i fix this error?

CODE follows :

#include <iostream>
#include <ostream>
#include <vector>
#include<string>
//#include <boost/shared_ptr.hpp>
#include "OS.hxx"
#include "Ram.hxx"
#include "Cpu.hxx"
#include "HardDisk.hxx"
#include "JobCreationFactory.hxx"
#include "Mouse.hxx"
#include "Monitor.hxx"
#include "Keyboard.hxx"

using namespace std;
typedef vector<int>LISTOFINT;
typedef LISTOFINT::iterator INT_ITER;

//namespace bo=boost;
//using bo::shared_ptr;
/* This is the main driver of the simulation,it makes all simulated devices available 
 and ready for use before operating system takes over(osTakeOver())
 */

int main(){

    int numberOfJobs = 0;
    bool simulate = false;
    string start;
    LISTOFINT schedulingAlgorithms; // 1 for SJF(Shortest Job first) and 2:for RR(Round Robbin)
    LISTOFINT numberOfResourcesAvailable;
    int mouseAvailable;
    int monitorAvailable;
    int keyboardAvailable;
    HardDisk HD;
    OS myOS;
    Cpu myCpu;
    Ram myRam;
    Mouse myMouse;
    Monitor myMonitor;
    Keyboard myKeyboard;
    JobCreationFactory j;

    j.createFiles(HD);
    j.createJobs(HD);

    //set defaut number of jobs to be used in the simulation .. allow user to input number of jobs
    cout << "***For simulation we use multiple instances of Mouse Monitor and Keyboard, this is actually the number of process a DeviceQ can handle at a g***\n";
    cout << "Enter number of Jobs to be used in the simulation (eg 40000) follwed by the number of available resources say ( 6 8 9) followed by 's' then hit Carriage return key>>>\n";
    while (cin >> numberOfJobs >> mouseAvailable >> monitorAvailable >> keyboardAvailable && !simulate) {
        simulate = true;
        HD.setNumberOfJobs(numberOfJobs);
    }   
    numberOfResourcesAvailable.push_back(mouseAvailable);
    numberOfResourcesAvailable.push_back(monitorAvailable);
    numberOfResourcesAvailable.push_back(keyboardAvailable);
    //setAvailable Resources
    //myOS.setAvailable(numberOfResourcesAvailable);

    INT_ITER aBegin = numberOfResourcesAvailable.begin();
    INT_ITER aEnd = numberOfResourcesAvailable.end();
    cout << "Initial number of resources Available (Mouse Monitor Keyboard):";
    for (; aBegin != aEnd; ++aBegin) {
        cout << *aBegin << " ";
    }
    cout << endl;
    /*simulate based on SJF then RR using the same number of resources then compare results
     *repeating the same algorithm a few more times would give a better comparison since this simulation
     *is entirely based on random number generation
    */
    schedulingAlgorithms.push_back(1);
    schedulingAlgorithms.push_back(2);
    INT_ITER sBegin = schedulingAlgorithms.begin();
    INT_ITER sEnd = schedulingAlgorithms.end();

    //at this point all devices are ready so an assumption can be made that 
    //BIOS has successfully checked devices hence BIOSdone = true
    //once everything is ready BIOS Loads OS
    cout << "SJF and RR are represented by:";
    for (; sBegin != sEnd; ++sBegin) {// for both algorithms
        cout << *sBegin <<" ";
        myOS.setSchedulingAlgorithm(*sBegin);
        myOS.osTakeOver(HD,myRam,myCpu,myMouse,myMonitor,myKeyboard);
    }
    cout << "respectively\n";
    cout << endl;
    //for now the smulation progress will be seen on the console

    return 0;

}

[possible duplicate](http://stackoverflow.com/q/5481409/283302). — Sam Miller, Mar 31 '11 at 00:44

score 3 · Answer 1 · edited May 23 '17 at 11:51

The easiest way is to look if you have defined this symbol

undefined reference to `JobCreationFactory::createFiles(HardDisk)'

In the JobCreationFactory.cxx.o translation unit. Most likely you have declared it in JobCreationFactory.hxx but have not defined it in the corresponding implementation.

based on your other question that this one is a near exact duplicate of, I think I know what's going on. In JobCreationFactory.cxx you are not defining the class methods, you are redeclaring them

class JobCreationFactory{
    int numOfJobs;
    int numOfFiles;
    int time;
    int size;
    LISTOFINT header;

    JobCreationFactory()
    :numOfJobs(0),time(0),size(0)
    {
    }

Don't do that, do this instead

JobCreationFactory::JobCreationFactory() : numOfJobs(0),time(0),size(0)
{

}

and so on, for all the methods declared in JobCreationFactory.h. If this concept is confusing to you, you might want to get a good book about C++.

Thanks, I have always thought i do that whenever i define the methods outside the class. — user599319, Mar 31 '11 at 01:06

score 1 · Answer 2 · answered Mar 31 '11 at 00:27

Linking errors are usually due to:

Forgetting to define the symbol/function. Some people simply forget to do the implementation on the .cpp file.
Defining the wrong symbol. It was supposed to be one thing but it was defined as another, very similar.
Not linking with the right library. If that function was not implemented by you, it means the symbol is defined somewhere else.

score 0 · Answer 3 · answered Mar 31 '11 at 00:16

0

Try to use IDE like Visual Studio or Code::Block, etc. That tools may help you with these compile and link problem.

answered Mar 31 '11 at 00:16

Jason

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What is the easiest way to resolve c++ linking error

3 Answers3