Undefined reference C++?

Question

New to c++, and trying to use a file our professor made for us and I can't use any of the functions it provides heres the code that gives an Undefined reference. I didn't include the function implementations but they again were provided so they are correct. I'm using codeblocks and all three files are in my sources folder. What is causing this?

#include <iostream>

using namespace std;
#include "random.h"


int main()
{

cout<< random_instance(6,2.5,1);
return 0;
}

this is the random.h

#ifndef RANDOM_H
#define RANDOM_H

#define TWO_PI 6.2831853071795864769252866

double * random_instance( int length, const double mu, const double sigma = 1 );
double gaussian_rand( const double mu, const double sigma );

#endif /* defined(RANDOM_H) */

How are you compiling it? You're likely forgetting to compile/link with the code your instructor provided. — Colonel Thirty Two, Mar 03 '15 at 01:51
yes it is, they are in different folders, both of which are in the sources folder if that matters — tokola, Mar 03 '15 at 01:54
You may this question and at-least one of its answers enlightening: [What is an undefined reference/unresolved external symbol error and how do I fix it?](http://stackoverflow.com/questions/12573816/what-is-an-undefined-reference-unresolved-external-symbol-error-and-how-do-i-fix) — WhozCraig, Mar 03 '15 at 01:55

Emil Laine · Answer 1 · 2015-03-03T02:03:23.433

0

The definition for random_instance is missing.

You should probably compile and link random.cpp too which should contain the definitions for the functions declared in random.h, maybe something like this:

g++ path/to/main.cpp path/to/random.cpp

In Code::Blocks there's probably a section somewhere where you can choose the files to compile and link.

edited Mar 03 '15 at 02:03

answered Mar 03 '15 at 01:51

Emil Laine

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Undefined reference C++?

1 Answers1