undefined error

[illario]

I get undefined error and I haven't got a clue how to fix it. Any help would be greatly appreciated. Important parts of codes are below:

nr.h

#include <vector>
using namespace std;

namespace NR {
  void polint(const std::vector<double> &xa, const std::vector<double> &ya, const double x, double &y, double &dy);
}

nr.cpp

#include "nr.h"

void polint(const std::vector<double> &xa, const std::vector<double> &ya, const double x, double &y, double &dy) {

vector<int>::size_type n = xa.size();
... Implementation ...

}

main.cpp

#include <iostream>
#include <iomanip>
#include <cmath>
#include "nr.h"
using namespace std;

int main(void) {
 unsigned int n;
 double x,y,dy;
 vector<double> xa(n);
 vector<double> ya(n);
 
 NR::polint(xa,ya,x,y,dy);

 ...
}

I cannot get it to compile.

main.cpp:(.text+0x509): undefined reference to `NR::polint(std::vector<double, std::allocator<double> > const&, std::vector<double, std::allocator<double> > const&, double, double&, double&)'
collect2: ld returned 1 exit status

[Moschops]

It is compiling. You cannot get it to link. Have you compiled nr.cpp and instructed the linker to link it as well as main.o?

[illario]

All three files are in the same directory. I compiled them as

g++ main.cpp nr.cpp -o main

with an output showed above.

And yes, separately main.cpp and nr.cpp are compiled well but not linked after.

[Moschops]

Try this in nr.cpp

#include "nr.h"

void NR::polint(const std::vector<double> &xa, const std::vector<double> &ya, const double x, double &y, double &dy) {

vector<int>::size_type n = xa.size();
... Implementation ...

}

[Lodger]

You're missing the namespace qualifier on your implementation

#include "nr.h"

void NR::polint(const std::vector<double> &xa, const std::vector<double> &ya, const double x, double &y, double &dy) {

vector<int>::size_type n = xa.size();
... Implementation ...

}

*edit* ninja'd!

[illario]

Solved! Thank you so much for your time!

[illario]

I cannot get it to link again. I was trying to make a template function from NR::polint as the following

nr.h

#include <vector>
using namespace std;

namespace NR {
  template <class T>
  void polint(const std::vector<T> &xa, const std::vector<T> &ya, const T x, T &y, T &dy);
}

nr.cpp

template <class T>
void NR::polint(const std::vector<T> &xa, const std::vector<T> &ya, const T x, T &y, T &dy) {

typename vector<T>::size_type n = xa.size();
... Implementation ...

}

main.cpp was not changed at all.

NR::polint(xa,ya,x,y,dy);

or

NR::polint<double>(xa,ya,x,y,dy);

lead to the same output:

undefined reference to `int NR::polint<double>(std::vector<double, std::allocator<double> > const&, std::vector<double, std::allocator<double> > const&, double, double&, double&)'

Any suggestions?!

[Peter87]

Templates has to be defined in the the same translation unit they are used so put the definition of NR::polint in the header file.

[illario]

Thank you.