c++ - Undefined reference to operator << in inherited class -
i'm trying overload << , >> operators polygon class , derived triangle class. problem compiler returning following error:
error: undefined reference `operator<<(std::ostream&, triangle const&)' i did define above operator however. have following line in triangle.h file:
std::ostream & operator << (std::ostream & os, triangle const&); this problem occurs triangle class. when remove line trying output triangle, program works correctly. there no problem outputting polygon. causing problem , how fix it? problem include hierarchy?
i think relevant files main.cpp, triangle.h, , triangle.cpp included full copy of code below in case error caused else. thank , patience.
main.cpp
#include <iostream> #include "triangle.h" using namespace std; int main() { triangle t (vertex (0, 0), vertex (5, 0), vertex (0, 5)); triangle l (t); cout << l[0] << endl; cout << "l: " << l << endl; //not working polygon p; p.add (vertex (0,0)); cout << "p: " << p << endl; //working return 0; } triangle.h
#include "polygon.h" #include <iostream> class triangle : public polygon { public: triangle(vertex = vertex(), vertex = vertex(), vertex = vertex()); triangle(const triangle &); double area() const; vertex operator[](size_t i) const; private: size_t size() const; void add(vertex iv); std::vector<vertex> v; }; std::ostream & operator << (std::ostream & os, triangle const&); std::istream & operator >> (std::istream & is, triangle & t); triangle.cpp
#include "triangle.h" #include <math.h> #include <cassert> triangle::triangle(vertex ta, vertex tb, vertex tc) { v.push_back(ta); v.push_back(tb); v.push_back(tc); } triangle::triangle(const triangle & t) { v=t.v; } double triangle::area() const { double a=sqrt((v[0].x-v[1].x)*(v[0].x-v[1].x)+(v[0].y-v[1].y)*(v[0].y-v[1].y)); double b=sqrt((v[1].x-v[2].x)*(v[1].x-v[2].x)+(v[1].y-v[2].y)*(v[1].y-v[2].y)); double c=sqrt((v[2].x-v[0].x)*(v[2].x-v[0].x)+(v[2].y-v[0].y)*(v[2].y-v[0].y)); double s=((a+b+c)/2); return sqrt(s*(s-a)*(s-b)*(s-c)); } vertex triangle::operator[] (std::size_t i) const { assert (i<3); return v[i]; } inline std::ostream & operator << (std::ostream & os, triangle const & t) { std::cout << "test" << std::endl; return os << t[0]; } std::istream & operator >> (std::istream & is, triangle & t) { vertex vx; (size_t = 0; < 3; ++i) { >> vx.x >> vx.y; //t.v.push_back(vx); } return is; } polygon.h
#include <iostream> #include <vector> #include "vertex.h" class polygon { public: // pre: // post: empty polygon created polygon(); // pre: // post: polygon created , initialized given polygon source polygon(const polygon & source); // pre: // post: return number of vertices in polygon std::size_t size() const; // pre: 0 <= < size() // post: return vertex in polygon vertex operator[](size_t i) const; // pre: // post: vertex added polygon void add(const vertex & v); private: std::vector<vertex> v; }; std::ostream & operator << (std::ostream & os, const polygon & p); std::istream & operator >> (std::istream & is, polygon & p); polygon.cpp
#include <cassert> #include "polygon.h" polygon::polygon() { v = std::vector<vertex> (); } polygon::polygon(const polygon & p) { v = p.v; } std::size_t polygon::size() const { return v.size(); } vertex polygon::operator[] (std::size_t i) const { assert(i < size()); return v[i]; } void polygon::add(const vertex & vx) { v.push_back(vx); } std::ostream & operator << (std::ostream & os, const polygon & p) { (std::size_t = 0; < p.size(); ++i) os << p[i] << " "; return os; } std::istream & operator >> (std::istream & is, polygon & p) { std::size_t n; vertex vx; >> n; (size_t = 0; < n; ++i) { >> vx.x >> vx.y; p.add(vx); } return is; } vertex.h
#include <iostream> struct vertex { double x, y; vertex(double ix = 0.0, double iy = 0.0) { x = ix; y = iy; } }; std::ostream & operator << (std::ostream & os, const vertex & v); vertex.cpp
#include "vertex.h" std::ostream & operator << (std::ostream & os, const vertex & v) { os << "(" << v.x << ", " << v.y << ")"; return os; }
here's problem:
// triangle.cpp inline std::ostream & operator << (std::ostream & os, triangle const & t) ^^^^^^ inline functions must defined in translation units use them, , defined in one. either remove inline, or move definition header make available anywhere used.
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