I am sure this is a trivial error. Nontheless I cannot find an error or a solution on Stackoverflow.
I have received above mentioned error for struct Transition, seemingly declared here :
Transition.h:
#ifndef ZOCK_TRANSITION_H
#define ZOCK_TRANSITION_H
#include <iostream>
#include "vec.h"
#include "dir.h"
#include "Board.h"
using std::ostream;
using std::endl;
struct Transition
{
vec fromv;
dir fromd;
vec tov;
dir tod;
Transition();
Transition(vec fromv, dir fromd, vec tov, dir tod);
friend ostream& operator<< (ostream& os, cost Transition& t);
};
Transition swap(Transition& t) const;
#endif// ZOCK_TRANSITION_H
Error Message is :
g++ -std=c++14 -I./inc -c src/Transition.cpp -o build/debug/Transition.o -g3
In file included from ./inc/Board.h:21:0,
from ./inc/Transition.h:19,
from src/Transition.cpp:12:
./inc/Map.h:29:9: error: ‘Transition’ was not declared in this scope
vector<Transition> transitions;
So lets look into Map.h:
#ifndef ZOCK_MAP_H
#define ZOCK_MAP_H
#include <string>
#include <vector>
#include "Transition.h"
using std::string;
using std::vector;
class Map
{
friend class Board;
private:
int height, width;
char ** fields;
vector<Transition> transitions;
public:
enum readfrom
{
str = 0,
file ,
NUM_READFROM //Leave last !
};
Map(string i, readfrom p);
};
#endif// ZOCK_MAP_H
It is unlikely that it is a compiler or linker error, since it seems every file was found correctly. Everything seems to be included correctly, so I am at a dead end.
What dows cause the error or what are common mistakes causing the error ?
Related
I have already checked StackOverflow to find the solution to my problem, but I think I might be missing something. I am trying to define a class in a header file (.h) and implement its methods in a cpp file (.cpp), but it does not work.
main.cpp:
#include <iostream>
#include "Message.h"
using namespace std;
int main()
{
Message *t = new (Message);
t->display();
return 0;
}
Message.h:
#ifndef MESSAGE_H_INCLUDED
#define MESSAGE_H_INCLUDED
class Message {
public:
void display();
};
#endif // MESSAGE_H_INCLUDED
Message.cpp:
#include "Message.h"
void Message::display() {
cout << "Hello!";
}
I don't understand why I keep getting the following error
undefined reference to 'Message::display()'
Compile this with the command g++ -std=c++11 Message.cpp main.cpp
I'm trying to learn how to use C++ and ODB following this tutorial:
http://www.codesynthesis.com/products/odb/doc/manual.xhtml#2
I've created a Person.hxx file where there is the declaration of class Person as persistent, then I've got thre files Person-odb: .cxx, .hxx, .ixx
Now I should compile Person-odb.cxx with
g++ -I/usr/lib/odb/i686-linux-gnu/include Person-odb.cxx
but it end with:
fatal error: odb/pgsql/version.hxx: No such file or directory. compilation terminated.
I see that there is a file version.hxx but there's no odb/pgsql directory...
what's wrong?
this is Person.hxx where I have defined the persistent class Person:
#ifndef PERSON_HXX
#define PERSON_HXX
#include <string>
#include <odb/core.hxx>
using namespace std;
#pragma db object
class Person {
private:
Person() {
}
friend class odb::access;
#pragma db id auto
unsigned long id_;
std::string email_;
std::string first_;
std::string last_;
unsigned short age_;
public:
Person(const std::string& first, const std::string& last,
unsigned short age);
/* getters */
const std::string& first() const;
const std::string& last() const;
unsigned short age() const;
const std::string& email() const;
/* setters */
void setAge(unsigned short);
void setFirst(const std::string&);
void setLast(const std::string&);
void setEmail(const std::string&);
};
#endif
then I must compile Person.hxx with odb compiler:
odb -d mysql --generate-query --generate-schema Person.hxx
and I get 4 files Person.odb.hxx, .cxx, .sql, .ixx
this is driver.cxx where I have the main program which persists objects:
#include <memory>
#include <iostream>
#include <odb/database.hxx>
#include <odb/transaction.hxx>
#include <odb/mysql/database.hxx>
#include "Person.hxx"
#include "Person-odb.hxx"
using namespace std;
using namespace odb;
int main(int argc, char* argv[]) {
try {
auto_ptr<database> db (new odb::mysql::database (argc, argv));
unsigned long marcoID, loryID, lucaID;
/*Create some persistent Person objects */
Person marco ("Marco", "Di Nicola", 26);
Person luca ("Luca", "La Sala", 22);
Person lory ("Lorenzo", "Vinci", 24);
transaction t (db->begin());
marcoID = db->persist(marco);
lucaID = db->persist(luca);
loryID = db->persist(lory);
t.commit();
} catch (const odb::exception& e) {
cerr << e.what() << endl;
return 1;
}
}
and this is the file Person-odb.hxx
// This file was generated by ODB, object-relational mapping (ORM)
// compiler for C++.
//
#ifndef PERSON_ODB_HXX
#define PERSON_ODB_HXX
#include <odb/version.hxx>
#if (ODB_VERSION != 20200UL)
#error ODB runtime version mismatch
#endif
#include <odb/pre.hxx>
#include "Person.hxx"
#include <memory>
#include <cstddef>
#include <odb/core.hxx>
#include <odb/traits.hxx>
#include <odb/callback.hxx>
#include <odb/wrapper-traits.hxx>
#include <odb/pointer-traits.hxx>
#include <odb/container-traits.hxx>
#include <odb/no-op-cache-traits.hxx>
#include <odb/result.hxx>
#include <odb/simple-object-result.hxx>
#include <odb/details/unused.hxx>
#include <odb/details/shared-ptr.hxx>
namespace odb
{
// Person
template <>
struct class_traits< ::Person >
{
static const class_kind kind = class_object;
};
template <>
class access::object_traits< ::Person >
{
...
#include "Person-odb.ixx"
#include <odb/post.hxx>
#endif // PERSON_ODB_HXX
everything seems to work fine when I perform:
c++ -c Person-odb.cxx
c++ -c driver.cxx
but in the end when I have to link all together with:
c++ -o driver driver.o Person-odb.o -lodb-mysql -lodb
I get:
"undefined reference to `Person::Person(std::basic_string, std::allocator > const&, std::basic_string, std::allocator > const&, unsigned short)'"
What seems to be your problem is that you didn't install ODB. The Installing ODB page should get you up and running.
You see a version.hxx file, but that's an input file for the ODB compilation process, not for including in your programs.
If you did install it, find out where on your system and add that folder to your compiler include path. Your compilation command then becomes
g++ -I/usr/lib/odb/i686-linux-gnu/include -I/path/to/odb/install/include Person-odb.cxx
Following your edits, I think the issue is that you're not linking to the Person object file, only the Person-odb one.
Compile Person.cxx with
g++ -c Person.cxx
and change your linking command to
g++ -o driver driver.o Person.o Person-odb.o -lodb-mysql -lodb
and the error should be fixed.
Please note that I don't know ODB. I'm trying to figure this out from a pure C++ perspective.
I got three .cpp files and two header files.
But when i compile them, meaning the Point.cpp, Data.cpp and main.cpp, it will say
Data.h:6:7 redefinition of Data at 'Data.h'
Data.h:6:7 previously definition of 'class Data'
Below is my Data.h(previously known as 2.h at above)
#include <iostream>
#include <string>
using namespace std;
class Data
{
private:
string sType;
public:
Data();
Data(string);
void setSType(string);
string getSType();
};
Below is my data.cpp
#include "Data.h"
Data::Data()
{
sType = "";
}
Data::Data(string s)
{
sType = s;
}
void Data::setSType(string ss)
{
sType = ss;
}
string Data::getSType()
{
return sType;
}
Below is my PointD.h (previously known as 3.h)
#include <iostream>
#include <string>
#include "Data.h"
using namespace std;
class PointD
{
private:
int x
Data data1;
public:
PointD();
PointD(int,Data);
void setX(int);
void setData(Data);
int getX();
Data getData();
};
Below is my PointD.cpp
#include "PointD.h"
PointD::PointD()
{
x = 0;
}
PointD::PointD(int xOrdinate,Data dd)
{
x = xOrdinate;
data1 = dd;
}
void PointD::setXordinate(int Xordinate)
{
x = Xordinate;
}
void PointD::setData(Data dd)
{
data1 = dd;
};
int PointD::getXordinate()
{
return x;
}
Data PointD::getData()
{
return data1;
}
This is my main.cpp
#include <iostream>
#include <string>
#include "Data.h"
#include "PointD.h"
using namespace std;
int main()
{
const int MAX_NUM = 20;
Data ldata[MAX_NUM];
PointD pointd[MAX_NUM];
//more codes..
}
But when i compile them, meaning the Point.cpp, Data.cpp and main.cpp, it will say
Data.h:6:7 redefinition of Data at 'Data.h'
Data.h:6:7 previously definition of 'class Data'
Can anybody let me know whats actually went wrong here..
You need to use include guards, or the easiest:
#pragma once
in your header files
See Purpose of Header guards for more background
Idea: 1.hpp
#ifndef HEADER_GUARD_H1_HPP__
#define HEADER_GUARD_H1_HPP__
// proceed to declare ClassOne
#endif // HEADER_GUARD_H1_HPP__
In each of your header files write:
#ifndef MYHEADERNAME_H
#define MYHEADERNAME_H
code goes here....
#endif
Its better like this:
#ifndef DATA_H /* Added */
#define DATA_H /* Added */
#include <iostream>
#include <string>
// using namespace std; /* Removed */
class Data
{
private:
std::string sType;
public:
Data();
Data( std::string const& ); // Prevent copy of string object.
void setSType( std::string& ); // Prevent copy of string object.
std::string const& getSType() const; // prevent copy on return
std::string& getSType(); // prevent copy on return
};
#endif /* DATA_H */
The big fix is adding ifndef,define,endif. The #include directive works as if copying and pasting the .h to that line. In your case the include from main.cpp are:
main.cpp
-> Data.h (1)
-> Point.h
-> Data.h (2)
At (2), Data.h has already been `pasted' into main.cpp at (1). The class declaration of Data, i.e. "class Data{ .... };" , appears twice. This is an error.
Adding include guards to the top and bottom of every .h are standard practice to avoid this problem. Don't think about it. Just do it.
Another change I'd suggest is to remove any "using namespace ..." lines from any .h . This breaks the purpose of namespaces, which is to place names into separate groups so that they are not ambiguous in cases where someone else wants an object or function with the same name. This is not an error in your program, but is an error waiting to happen.
For example, if we have:
xstring.h:
namespace xnames
{
class string
{
...
};
}
Foo.h
#include <xstring>
using namespace xnames;
...
test.cxx:
#include "Foo.h"
#include "Data.h" // Breaks at: Data( string ); -- std::string or xnames::string?
...
void test()
{
string x; // Breaks. // std::string or xnames::string?
}
Here the compiler no longer knows whether you mean xnames::string or std::string. This fails in test.cxx, which is fixable by being more specific:
void test()
{
std::string x;
}
However, this compilation still now breaks in Data.h. Therefore, if you provide that header file to someone, there will be cases when it is incompatible with their code and only fixable by changing your header files and removing the "using namespace ...;" lines.
Again, this is just good coding style. Don't think about it. Just do it.
Also, in my version of Data.h, I've changed the method parameters and return types to be references (with the &). This prevents the object and all of its state from being copied. Some clever-clogs will point our that the string class's is implementation prevents this by being copy-on-write. Maybe so, but in general, use references when passing or returning objects. It just better coding style. Get in the habit of doing it.
I have started working on a project that incorporates some of boost libraries(thread and MPI).
I am going to use boost multi_index in one of the modules which is not using boost at all.FYI this project has not used boost multi index before)
as soon as I tried to include
boost/multi_index_container.hpp
to the file and built the projects, I received a number of errors starting with the following:
Building CXX object CMakeFiles/SimMobility.dir/main.cpp.o
/usr/bin/c++ -fmessage-length=0 -DBOOST_NO_HASH -O0 -g -I/usr/include/postgresql -I/usr/include/soci -I/usr/include/soci/postgresql -I/usr/include/xsd -I/home/vahid/workspace/Basic__Multi_index -o CMakeFiles/SimMobility.dir/main.cpp.o -c /home/vahid/workspace/Basic__Multi_index/main.cpp
In file included from /usr/include/boost/multi_index/detail/node_type.hpp:22:0,
from /usr/include/boost/multi_index/detail/index_base.hpp:21,
from /usr/include/boost/multi_index/detail/base_type.hpp:21,
from /usr/include/boost/multi_index_container.hpp:33,
from /home/vahid/workspace/Basic__Multi_index/geospatial/RoadNetwork.hpp:10,
from /home/vahid/workspace/Basic__Multi_index/main.cpp:25:
/usr/include/boost/multi_index/detail/header_holder.hpp:41:16: error: expected unqualified-id before ‘)’ token
/usr/include/boost/multi_index/detail/header_holder.hpp: In constructor ‘boost::multi_index::detail::header_holder<NodeTypePtr, Final>::header_holder()’:
/usr/include/boost/multi_index/detail/header_holder.hpp:35:32: error: expected primary-expression before ‘)’ token
may I know what the problem is? is it cmake not finding what it needs? any idea how to solve it?
Edit:
in case you want to have a look at the source code, here is a simplified version:
RoadNetwork.hpp:
#pragma once
#include <iostream>
#include <vector>
#include <set>
#include <boost/multi_index_container.hpp> //causing problem!!!!!!!
namespace geo {class Links_pimpl;}
namespace sim_mob
{
//Forward declarations
class Node;
class UniNode;
class MultiNode;
class Point2D;
class Link;
namespace aimsun
{
//Forward declaration
class Loader;
}
//typedef multi_index_container<
//sim_mob::Link,
// indexed_by<
// random_access<>,
//// ordered_unique< member<sim_mob::Link, std::string, &sim_mob::Link::linkID> >
// >
//> Link_m;
class RoadNetwork {
public:
RoadNetwork() { drivingSide=DRIVES_ON_LEFT; } //TEMP
sim_mob::Node* locateNode(const sim_mob::Point2D& position, bool includeUniNodes=false, int maxDistCM=100) const;
private:
std::vector<sim_mob::MultiNode*> nodes;
std::vector<sim_mob::Link*> links;
std::vector<sim_mob::MultiNode*>& getNodesRW() { return nodes; }
std::set<sim_mob::UniNode*>& getUniNodesRW() { return segmentnodes; }
std::vector<sim_mob::Link*>& getLinksRW() { return links; }
friend class sim_mob::aimsun::Loader;
friend class geo::Links_pimpl;
};
}
Thank you your kind help
vahid
I modified your header to look like this:
#pragma once
#include <iostream>
#include <vector>
#include <set>
#include <boost/multi_index_container.hpp> //causing problem!!!!!!!
using boost::multi_index_container;
namespace geo {class Links_pimpl;}
namespace sim_mob
{
//Forward declarations
class Node;
class UniNode;
class MultiNode;
class Point2D;
class Link;
namespace aimsun
{
//Forward declaration
class Loader;
}
//typedef multi_index_container<
//sim_mob::Link,
// indexed_by<
// random_access<>,
// ordered_unique< member<sim_mob::Link, std::string, &sim_mob::Link::linkID> >
// >
//> Link_m;
class RoadNetwork {
int drivingSide;
enum side { DRIVES_ON_LEFT, DRIVES_ON_RIGHT};
public:
RoadNetwork() { drivingSide=DRIVES_ON_LEFT; } //TEMP
sim_mob::Node* locateNode(const sim_mob::Point2D& position, bool includeUniNodes=false, int maxDistCM=100) const;
private:
std::vector<sim_mob::MultiNode*> nodes;
std::vector<sim_mob::Link*> links;
std::set<sim_mob::UniNode*> segmentnodes;
std::vector<sim_mob::MultiNode*>& getNodesRW() { return nodes; }
std::set<sim_mob::UniNode*>& getUniNodesRW() { return segmentnodes; }
std::vector<sim_mob::Link*>& getLinksRW() { return links; }
friend class sim_mob::aimsun::Loader;
friend class geo::Links_pimpl;
};
}
Then I included it in a small file that instantiated a RoadNetwork object:
#include <iostream>
#include "roadnetwork.hpp"
int main() {
sim_mob::RoadNetwork roads;
return 0;
}
This compiled, linked, and executed (though produced no output).
Not entirely sure what problem you're encountering...
I encountered the same problem and tracked it down. Do you have by chance a #define final somewhere in your sources before including boost/multi_index.hpp or a -Dfinal in your compiler settings? In my case that was the problem, I use the C++11 keywords final and override in my classes and had to define them when using older compilers.
Or, maybe it's some other identifier used by multi_index that you have defined somewhere. You could dump all your defined macros as described here and check if disabling one of them helps.
I also encountered similar problem.
I got compile error in
multi_index header_holder file.
warning : final key word is blah... blah...
So I changed the
#include <boost/xxxxx>
position to other place.
( ex: stdafx.h etc ... )
Try this one.
Problem fixed. Thanks a lot!
I am having the following error in the code shown below:
Error is as follows:
$ g++ main.cpp Neighbor.cpp Graph.cpp
/tmp/ccclDcUN.o: In function main':
main.cpp:(.text+0xc1): undefined reference toGraph::add(int, Neighbor&)'
main.cpp:(.text+0xd3): undefined reference to `Graph::add(int, Neighbor&)'
collect2: ld returned 1 exit status
what could be going wrong?
// FILENAME: Graph.cpp
#include "Neighbor.h"
#include "Graph.h"
template <typename NS>
void Graph<NS>::add(int id,NS& n){
if(id>=adj_list.size())
while(adj_list.size()<id+1)
adj_list.push_back(list<NS>());
adj_list[id].push_back(n);
}
template <typename NS>
void Graph<NS>::remove(int id,NS& n){
if(id<adj_list.size()){
adj_list[id].remove(n);
}
}
// FILENAME: Graph.h
#ifndef GRAPH_H
#define GRAPH_H
#include "utils.h"
#include <vector>
#include <list>
class Neighbor;
template <typename NS>
class Graph {
private:
std::vector<std::list<NS> > adj_list;
public:
void add(int,NS&);
void remove(int,NS&);
inline typename std::vector<std::list<NS> >::iterator begin() { return adj_list.begin(); }
inline typename std::vector<std::list<NS> >::iterator end() { return adj_list.end(); }
};
#endif
// FILENAME: Neighbor.cpp
#include "Neighbor.h"
#include <iostream>
Neighbor::Neighbor(int id,float e,float p):id(id),edge_cost(e),price(p){}
bool operator==(const Neighbor& n1,const Neighbor& n2) {
if(&n1==&n2) return true;
return false;
}
ostream& operator<<(ostream& ostr,const Neighbor& n1) {
ostr<<"["<<n1.id<<","<<n1.price<<","<<n1.edge_cost<<"]";
return ostr;
}
// FILENAME: Neighbor.h
#ifndef NEIGHBOR_H
#define NEIGHBOR_H
#include <iosfwd>
class Neighbor {
private:
int id;
float edge_cost;
float price;
public:
Neighbor(int,float,float p=0.0);
friend bool operator==(const Neighbor&,const Neighbor&);
friend std::ostream& operator<<(std::ostream&,const Neighbor&);
};
#endif
// FILENAME: utils.h
#ifndef UTILS_H
#define UTILS_H
#include <iostream>
#include <fstream>
#include <stack>
#include <queue>
#include <vector>
#include <list>
#include <string>
#include <algorithm>
namespace utility {
typedef std::pair<int,int> ii;
typedef std::vector<int> vi;
typedef std::vector<ii> vii;
typedef std::vector<vii> vvii;
typedef std::stack<int> si;
typedef std::queue<int> qi;
}
#define UTILITY_TR(c,i) for(typeof((c).begin()) i = (c).begin() ; i!=(c).end() ; ++i )
#define UTILITY_ALL(c) (c).begin(),(c).end()
#define UTILITY_CPRESENT(c,x) (find(all(c),x) != (c).end())
#endif
// FILENAME: main.cpp
#include "utils.h"
#include "Neighbor.h"
#include "Graph.h"
using namespace std;
int main() {
Graph<Neighbor> graph;
Neighbor n1(1,10);
Neighbor n2(0,10);
graph.add(0,n1);
graph.add(1,n2);
cout<<"Printing graph"<<endl;
cout<<"--------------"<<endl;
UTILITY_TR(graph,it) {
UTILITY_TR(*it,n) {
cout<<*n<<endl;
}
}
};
What I usually do is manually verify the symbol exists in the library:
objdump --syms foo.o
This will output a list of symbols contained in the .o file... (since it's a link error, you should have .o files... (make sure you pass -c to g++ to get it to stop after compilation))... Then you can just visually verify the object has the symbols you think it does...
You need to have the definition of Graph's functions (add and remove) in the .h file so that the linker can find it.
I try to think of templates like envelopes. It's nonsensical to send it (compile) before you put in a letter (defined type). Seeing as cpp files are what is compiled, it makes sense that there shouldn't be cpp files for templated types.
HTH!