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Undefined symbols for architecture x86_64

ProgrammerSoul (29)
Why is it that every time I try to run my code, I get the following problem?

g++ -Wall -fexceptions -g -Iinclude -c /Users/Soul/Documents/School/Program1/main.cpp -o obj/Debug/main.o
g++ -o bin/Debug/Program1 obj/Debug/main.o obj/Debug/src/Vector.o
Undefined symbols for architecture x86_64:
"Vector<int>::Vector(int, int const&)", referenced from:
_main in main.o
"Vector<int>::~Vector()", referenced from:
_main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

The constructor doesn't seem to work for some reason.

main.cpp
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#include <iostream>
#include "Vector.h"

using namespace std;

int main(){
    Vector<int> testvec(4,5);
    delete testvec.data_val;
    return 0;
}


Vector.h
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#ifndef VECTOR_H
#define VECTOR_H

template <class T>
class Vector{
    public:
        T *data_val;

        Vector();
        Vector(int n,const T& val);
        Vector(const Vector& other);
        virtual ~Vector();
    protected:
    private:
};

#endif // VECTOR_H


Vector.cpp
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#include "Vector.h"

template <class T>
Vector<T>::Vector(){
    data_val = new T[0];
}

template <class T>
Vector<T>::Vector(int n,const T& val){
    data_val = new T[n];
    for(int index = 0; index < n; index++)
        data_val[index];
}


template <class T>
Vector<T>::Vector(const Vector& other){
    //copy ctor
}

template <class T>
Vector<T>::~Vector(){
    delete data_val;
}
Last edited on
jlb (4973)
Try putting the implementations into the header file. When dealing with template classes both the implementation and definition should be in the same file.

ProgrammerSoul (29)
I did that, but the constructor won't allocate memory for dataval. When the program runs this is my output:

Last login: Mon Sep 28 11:03:30 on ttys000
/Applications/CodeBlocks.app/Contents/MacOS/cb_console_runner DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:. /Users/Soul/Documents/School/Program1/bin/Debug/Program1
Christians-MBP:~ Soul$ /Applications/CodeBlocks.app/Contents/MacOS/cb_console_runner DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:. /Users/Soul/Documents/School/Program1/bin/Debug/Program1
Program1(4716,0x7fff786d0300) malloc: *** error for object 0x7fdef3404af0: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
0
Process returned -1 (0xFFFFFFFF) execution time : 0.294 s
Press ENTER to continue.

Updated main.cpp
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#include <iostream>
#include "Vector.h"

using namespace std;

int main(){
    Vector<int> testvec(4,5);
    cout << testvec.dataval[2];
    delete testvec.dataval;
    return 0;
}


Updated Vector.h
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#ifndef VECTOR_H
#define VECTOR_H

template <class T>
class Vector{
    public:
        T *dataval;

        Vector();
        Vector(int n,const T& val);
        Vector(const Vector& other);
        virtual ~Vector();
    protected:
    private:
};

//Imlementations
template <class T>
Vector<T>::Vector(){
    dataval = new T[0];
}

template <class T>
Vector<T>::Vector(int n,const T& val){
    dataval = new T[n];
    for(int index = 0; index < n; index++)
        dataval[index];
}


template <class T>
Vector<T>::Vector(const Vector& other){
    //copy ctor
}

template <class T>
Vector<T>::~Vector(){
    delete dataval;
}

#endif // VECTOR_H
jlb (4973)
Try removing the delete testvec.dataval; from main(), let your destructor do it's job.
ProgrammerSoul (29)
Thanks, you're a lifesaver
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