Weird Linker Error

Question

For some reason, i get a linker error. my distance.cpp compiles perfectly however same cannot be said for main.cpp this is the error i get:

Compiler: Default compiler
Executing  g++.exe...
g++.exe "C:\Users\Himalaya\Desktop\C++\testdistance\main.cpp" -o "C:\Users\Himalaya\Desktop\C++\testdistance\main.exe"    -I"C:\Dev-Cpp\lib\gcc\mingw32\3.4.2\include"  -I"C:\Dev-Cpp\include\c++\3.4.2\backward"  -I"C:\Dev-Cpp\include\c++\3.4.2\mingw32"  -I"C:\Dev-Cpp\include\c++\3.4.2"  -I"C:\Dev-Cpp\include"   -L"C:\Dev-Cpp\lib" 
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x13b):main.cpp: undefined reference to `Distance::Distance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x150):main.cpp: undefined reference to `Distance::setInches(double)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x16d):main.cpp: undefined reference to `Distance::Distance(int, double)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x18a):main.cpp: undefined reference to `Distance::Distance(int, double)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x19c):main.cpp: undefined reference to `Distance::Distance(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x1af):main.cpp: undefined reference to `Distance::setFeet(int)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x1c6):main.cpp: undefined reference to `Distance::Distance(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x1d8):main.cpp: undefined reference to `Distance::Distance(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x1ea):main.cpp: undefined reference to `Distance::Distance(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x1fc):main.cpp: undefined reference to `Distance::Distance(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x3e1):main.cpp: undefined reference to `Distance::Distance(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x3fc):main.cpp: more undefined references to `Distance::Distance(Distance const&)' follow
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x52a):main.cpp: undefined reference to `Distance::Distance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x54c):main.cpp: undefined reference to `Distance::operator+(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x598):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x5c0):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x5e8):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x7f8):main.cpp: undefined reference to `Distance::Distance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x81a):main.cpp: undefined reference to `Distance::operator-(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x866):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x88e):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x8b6):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xac7):main.cpp: undefined reference to `Distance::Distance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xb02):main.cpp: undefined reference to `Distance::operator+(Distance const&)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xb97):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xc3a):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xdc9):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xe9f):main.cpp: undefined reference to `Distance::getInches()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xeb6):main.cpp: undefined reference to `Distance::getFeet()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xfcd):main.cpp: undefined reference to `Distance::Distance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xfd8):main.cpp: undefined reference to `Distance::Distance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xfe3):main.cpp: undefined reference to `Distance::getInches()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0xff4):main.cpp: undefined reference to `Distance::getFeet()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x101b):main.cpp: undefined reference to `Distance::getInches()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x102c):main.cpp: undefined reference to `Distance::getFeet()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x105d):main.cpp: undefined reference to `Distance::setInches(double)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x107a):main.cpp: undefined reference to `Distance::setInches(double)'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x10a0):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x10c8):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x10f0):main.cpp: undefined reference to `Distance::showDistance()'
C:\Users\Himalaya\AppData\Local\Temp/cckxbaaa.o(.text+0x111b):main.cpp: undefined reference to `Distance::showDistance()'
collect2: ld returned 1 exit status

Execution terminated

Here is my codes;

distance.cpp

#include <cmath>
#include <sstream>
#include <string>
#include "distance.h"

using namespace std;



Distance::Distance()
{
    feet = 0;
    inches = 0;
}

Distance::Distance(int ft, double in)
{
    this->feet = ft;

    if(in >= 12)
    {
        while(in >= 12) // pull as many feet as possible out of inches
        {
            this->feet += 1;
            in -= 12;
        }
        this->inches = in;  // store remainder
    }
    else
    {
        this->inches = in;
    }
}

Distance::Distance(const Distance &dist)
{
    this->feet = dist.feet;
    this->inches = dist.inches;
}

void Distance::setInches(double in)
{
    if(in >= 12)
    {
        while(in >= 12) // pull as many feet as possible out of inches
        {
            this->feet += 1;
            in -= 12;
        }
        this->inches = in;  // store remainder
    }
    else
    {
        this->inches = in;
    }
}

double Distance::getInches()
{
    return this->inches;
}

void Distance::setFeet(int ft)
{
    this->feet = ft;
}

int Distance::getFeet()
{
    return this->feet;
}

bool Distance::operator==(Distance &dist)
{
    if((this->feet == dist.feet) && (this->inches == dist.inches))
    {
        return true;
    }
    else
    {
        return false;
    }
}

Distance Distance::operator+(const Distance &dist)
{
    Distance dist_return;
    double total_inches = 0;
    dist_return.feet = this->feet + dist.feet;
    total_inches = this->inches + dist.inches;
    if(total_inches >= 12)
    {
        while(total_inches >= 12) // pull as many feet as possible out of inches
        {
            dist_return.feet += 1;
            total_inches -= 12;
        }
        dist_return.inches = total_inches;
    }
    else
    {
        dist_return.inches = this->inches + dist.inches;
    }

    return dist_return;
}

Distance Distance::operator-(const Distance &dist)
{
    Distance dist_return;
    int temp_feet = this->getFeet(); // copy "this" so we can do math and show properly
    double temp_inches = this->getInches();

    dist_return.feet = temp_feet - dist.feet;
    dist_return.inches = temp_inches - dist.inches;

    dist_return.feet = abs(dist_return.feet);
    dist_return.inches = abs(dist_return.inches);  // distance is never negative, and - means difference, so 12 - 20 = 8

    return dist_return;
}

string Distance::showDistance()
{
    string str_return = "";
    std::ostringstream temp_str_holder;

    if(this->feet > 0)  // only print feet if we have any
    {
        temp_str_holder.str("");  // clear out ostringstream
        temp_str_holder << this->feet;
        str_return += temp_str_holder.str();

        if(this->feet == 1)
        {
            str_return += " foot";
        }
        else
        {
            str_return += " feet";
        }
    }

    if(this->inches > 0)  // only print inches if we have any
    {
        if(this->feet > 0)
        {
            str_return += " ";  // if we have both feet and inches, print spacer between terms
        }

        temp_str_holder.str("");  // clear out ostringstream
        temp_str_holder << this->inches;
        str_return += temp_str_holder.str();

        if(this->inches == 1)
        {
            str_return += " inch";
        }
        else
        {
            str_return += " inches";
        }
    }

    if((this->feet == 0) && (this->inches == 0))  // if 0 feet 0 inches, just say 0 inches
    {
        str_return = "0 inches";
    }

    return str_return;
}

distance.h

#ifndef DISTANCE_H
#define DISTANCE_H


#include <cmath>
#include <sstream>
#include <string>

using namespace std;

class Distance
{
private:
    double inches;
    int feet;

public:
    Distance();
    Distance(int ft, double in);
    Distance(const Distance &dist);
    void setInches(double in);
    double getInches();
    void setFeet(int ft);
    int getFeet();
    bool operator==(Distance &dist);
    Distance operator+(const Distance &dist);
    Distance operator-(const Distance &dist);
    string showDistance();

};

#endif // DISTANCE_H

and my main.cpp which the program actually suppose to run from, however it gives me that weird error stated above.

#include <iostream>
#include <iomanip>
#include <string>
#include "distance.h"


using namespace std;

void addDistances(Distance dist1, Distance dist2);
void subtractDistances(Distance dist1, Distance dist2);
void sumDistanceArray(Distance dist_array[]);
void plotDistanceArray(Distance dist_array[]);
void calcRectangle(Distance dist1, Distance dist2);
//void calcVolume(Distance dist1, Distance dist2);

int main()
{
    Distance dist1;  // showing initialization using defaults
    dist1.setInches(6.7);
    Distance dist2(1,7);  // showing initialization to a distance
    Distance dist3(0,34);  // showing the auto-conversion of inches to feet as needed
    Distance dist4(dist3);  // showing initialization to another distance object's values
    dist4.setFeet(4);
    Distance dist_array[4] = {dist1, dist2, dist3, dist4};
    int menu_entry;
    bool menu_exit = false;

    do
    {
        //display menu
        cout << endl << endl << endl;
        cout << "***** Main Menu *****" << endl;
        cout << "1: Add two distances" << endl;
        cout << "2: Subtract two distances" << endl;
        cout << "3: Sum an array of distances" << endl;
        cout << "4: Plot an array of distances" << endl;
        cout << "5: Calculate the perimeter and area and volume" << endl;
        cout << "6: Exit" << endl;
        cout << "Please enter the number of your selection: ";
        cin >> menu_entry;


        // check entry, warn and promt again if invalid
        if ((menu_entry < 1) || (menu_entry > 6))
        {
            cout << endl;
            cout << "Invalid entry! Please try again." << endl;
            continue;
        }


        switch (menu_entry)
        {
            case 1:
                addDistances(dist2, dist3);
                break;
            case 2:
                subtractDistances(dist2, dist3);
                break;
            case 3:
                sumDistanceArray(dist_array);
                break;
            case 4:
                plotDistanceArray(dist_array);
                break;
            case 5:
                calcRectangle(dist2, dist3);
                break;
            case 6:
            default:
                menu_exit = true;  
                break;
        }
    }
    while(!menu_exit);

    return 0;
}

void addDistances(Distance dist1, Distance dist2)
{
    Distance dist_total;
    dist_total = dist1 + dist2;

    cout << endl;
    cout << "The sum of " << dist1.showDistance() << " and " << dist2.showDistance() << " is "
         << dist_total.showDistance() << endl;
}

void subtractDistances(Distance dist1, Distance dist2)
{
    Distance dist_total;
    dist_total = dist1 - dist2;

    cout << endl;
    cout << "The difference of " << dist1.showDistance() << " and " << dist2.showDistance() << " is "
         << dist_total.showDistance() << endl;
}

void sumDistanceArray(Distance dist_array[])
{
    int i;
    int num_distances = 4;
    Distance dist_total;
    for(i=0; i<num_distances; i++)
    {
        dist_total = dist_total + dist_array[i];
    }

    cout << endl;
    cout << "The sum of: " << endl;
    for(i=0; i<num_distances; i++)
    {
        cout << dist_array[i].showDistance() << endl;
    }
    cout << "is " << dist_total.showDistance() << endl;
}

void plotDistanceArray(Distance dist_array[])
{
    int i;
    int j;
    double inches;
    double bar_percentage;  
    double bar_length;  
    int num_distances = 4;
    int num_feet_max = 6;  
    int num_max_disp_columns = 60;  

    cout << endl;
    cout << "Plot of the array of distances : " << endl;

    for(i=0; i<num_distances; i++)
    {
        cout << setw(20) << dist_array[i].showDistance() << " ";

        inches = dist_array[i].getInches() + (12 * dist_array[i].getFeet());
        bar_percentage = inches / (num_feet_max*12);
        bar_length = bar_percentage * num_max_disp_columns;  // calculate bar length

        for(j=0; j<(bar_length+1); j++)
        {
            cout << "#";  // draw bar
        }
        cout << endl;
    }
}

void calcRectangle(Distance dist1, Distance dist2)
{
    Distance rect_area;
    Distance rect_perimeter;
    double inches1;
    double inches2;

    inches1 = dist1.getInches() + (12 * dist1.getFeet());
    inches2 = dist2.getInches() + (12 * dist2.getFeet());

    rect_area.setInches(inches1 * inches2);
    rect_perimeter.setInches((2 * inches1) + (2 * inches2));

    cout << endl;
    cout << "A rectangle with dimensions " << dist1.showDistance() << " and " << dist2.showDistance() << " has an area of "
         << rect_area.showDistance() << " and a perimeter of " << rect_perimeter.showDistance() << endl;
}

what is the problem? what does cckxbaaa.o(.text+0x13b) mean?? This is something i have not encountered before that is why i am seeking for your help. All these 3 files are in the same folder/path, why does it giving me this error?

Answer 1

The linker does not seem to link the compiled object of distance.cpp. So distance.o is missing under the -o options

Check this and compare your linker call

http://homepages.gac.edu/~mc38/2001J/documentation/g++.html

(Another small issue, you do not need to include cmath, sstream and string in the distance.cpp file.

Answer 2

Don't worry about the meaning of cckxbaaa.o(.text+0x13b): that's hackerhead stuff. The important part is the rest of the message: "undefined reference to Distance::Distance()" and the rest. It means that the linker hasn't seen the object file that has the Distance member functions in it.

Unlike Java, C++ doesn't hunt around your folders to try to figure out what you wanted to use. To compile and link the executable:

g++ main.cpp distance.cpp

That compresses two steps into one. Step 1: compile each source file into an object file. Step 2: link the object files and the standard library together to produce an executable file. It's that last step that's failing, presumably because the linker command line isn't correct.