"Undefined reference" trying to reference an static field

Question

I have this definition for my Test class:

#ifndef TEST_H
#define TEST_H

#include <iostream>
#include <cstdlib>
#include <ctime>
#include <fstream>

class Test {
      public:
          static bool testAll(bool debug = false);           
      private:
          static bool testVector2D(bool debug = false);
          static bool testPolygon(bool debug = false);
          static bool testRectangle(bool debug = false);
          static bool testMap(bool debug = false);

          static std::ofstream outStream;
          static std::ifstream inStream;

          static void prepareWriting();
          static void prepareReading();

          const char tempFileName[];
};

When I try to use Test::outStream or Test::inStream, for example here:

void Test::prepareWriting() {
    if (Test::inStream.is_open()) {
        Test::inStream.close();
    }
    Test::outStream.open(testFileName,ios::out); 
}

I get this msg: "undefined reference to `Test::inStream'"

I have read something about inicializating the static members in the .cpp file, but I don't know how to do that with fstream's

Not an exact dupe, but this contains relevant info: http://stackoverflow.com/questions/185844/initializing-private-static-members — Vaughn Cato, Feb 25 '12 at 17:49
In C++ you don't have to make the functions static members of a class. You can use a namespace instead. — Bo Persson, Feb 25 '12 at 17:49
This question is answered by [a C++ SO FAQ entry](http://loungecpp.wikidot.com/faq#toc4) — Seth Carnegie, Feb 25 '12 at 17:49

score 3 · Accepted Answer · answered Feb 25 '12 at 17:46

3

You need to define the streams where you define the other Test methods:

std::ofstream Test::outStream;
std::ifstream Test::inStream;

answered Feb 25 '12 at 17:46

smparkes

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"Undefined reference" trying to reference an static field

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