#include <iostream>
class t1
{
public:
~t1();
static t1& fun();
private:
t1()
{
}
};
t1& t1::fun()
{
return t1();
}
int main()
{
t1::fun();
return 0;
}
I am getting unresolved external symbol. please help. the errors are below
Error 2 error LNK2019: unresolved external symbol "public: __thiscall t1::~t1(void)" (??1t1##QAE#XZ) referenced in function "public: static class t1 & __cdecl t1::fun(void)" (?fun#t1##SAAAV1#XZ) D:\LXI\LXIRef\RefDesign_V01.00\Software\Solution\TestWebServer\TestWebServer.obj TestWebServer
Error 3 error LNK1120: 1 unresolved externals D:\LXI\LXIRef\RefDesign_V01.00\Software\Solution\Debug\TestWebServer.exe 1 1 TestWebServer
Give definitions to constructor and destructor.
#include <iostream>
class t1
{
public:
~t1() {} // <<<< defined here
static t1& fun();
private:
t1() {} // << defined here
};
t1& t1::fun()
{
return t1();
}
int main()
{
t1::fun();
return 0;
}
Related
This question already has answers here:
Why can templates only be implemented in the header file?
(17 answers)
Closed 5 years ago.
i'm just writing an array class as practice in Microsoft Visual Studio 2010 but i'm getting some annoying errors. here they are:
1>test.obj : error LNK2019: unresolved external symbol "public: __thiscall arrays<int>::~arrays<int>(void)" (??1?$arrays#H##QAE#XZ) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "public: int & __thiscall arrays<int>::operator[](int)" (??A?$arrays#H##QAEAAHH#Z) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "public: bool __thiscall arrays<int>::operator==(class arrays<int> const &)const " (??8?$arrays#H##QBE_NABV0##Z) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "public: int const & __thiscall arrays<int>::operator=(class arrays<int> const &)" (??4?$arrays#H##QAEABHABV0##Z) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "public: __thiscall arrays<int>::arrays<int>(class arrays<int> const &)" (??0?$arrays#H##QAE#ABV0##Z) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "class std::basic_istream<char,struct std::char_traits<char> > & __cdecl operator>>(class std::basic_istream<char,struct std::char_traits<char> > &,class arrays<int> const &)" (??5#YAAAV?$basic_istream#DU?$char_traits#D#std###std##AAV01#ABV?$arrays#H###Z) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class arrays<int> const &)" (??6#YAAAV?$basic_ostream#DU?$char_traits#D#std###std##AAV01#ABV?$arrays#H###Z) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "public: int __thiscall arrays<int>::getsize(void)const " (?getsize#?$arrays#H##QBEHXZ) referenced in function _wmain
1>test.obj : error LNK2019: unresolved external symbol "public: __thiscall arrays<int>::arrays<int>(int)" (??0?$arrays#H##QAE#H#Z) referenced in function _wmain
1>c:\users\bm\documents\visual studio 2010\Projects\arrays\Debug\arrays.exe : fatal error LNK1120: 9 unresolved externals
how can I fix them?
here is my code:
arrays.h
#ifndef ARRAYS_H
#define ARRAYS_H
#include <iostream>
using namespace std;
template <typename T>
class arrays{
friend ostream &operator<<(ostream &output, const arrays &a);
friend istream &operator>>(istream &input, const arrays &a);
public:
arrays(int = 10);
arrays(const arrays &);
~arrays();
int getsize() const;
const T &operator=(const arrays &);
bool operator==(const arrays &) const;
bool operator!=(const arrays &right) const{
return !((*this)==right);
}
T &operator[](int);
T operator[](int) const;
private:
int size;
T *ptr;
};
#endif
arrays.cpp
#include "stdafx.h"
#include <iostream>
#include "arrays.h"
#include <cstdlib>
using namespace std;
template <typename T>
arrays<T>::arrays(int mysize){
size = mysize;
ptr = new(int[size]);
for(int i = 0; i< size; i++)
ptr[i] = 0;
}
template <typename T>
arrays<T>::arrays(const arrays<T> &myarray){
size = myarray.size;
ptr = new(int[size]);
for(int i = 0; i< size; i++){
ptr[i] = myarray.ptr[i];
}
}
template <typename T>
arrays<T>::~arrays(){
delete [] ptr;
}
template <typename T>
int arrays<T>::getsize() const {
return size;
}
template <typename T>
const T &arrays<T>::operator=(const arrays<T> &right){
if ( &right != this){
if(size != right.size){
delete [] ptr;
size= right.size;
ptr = new(int[size]);
}
for(int i =0; i < size; i++)
ptr[i] = right.ptr[i];
}
return *this;
}
template <typename T>
bool arrays<T>::operator==(const arrays<T> &right) const{
if(right.size != size)
return false;
for(int i = 0; i<size; i++)
if(ptr[i] != right.ptr[i])
return false;
return true;
}
template <typename T>
T &arrays<T>::operator[](int subscript) {
if(subscript < 0 || subscript >= size){
cout << "error: subscript out of range";
}
return ptr[subscript];
}
template <typename T>
T arrays<T>::operator[](int subscript) const {
if(subscript < 0 || subscript >= size){
cout << "error: subscript out of range";
exit(1);
}
return ptr[subscript];
}
template <typename T>
istream &operator>>(istream &input, const arrays<T> &a){
for(int i = 0; i< a.size; i++)
input >> a.ptr[i];
return input;
}
template <typename T>
ostream &operator<<(ostream &output, arrays<T> &a){
for(int i= 0; i<a.size;i++)
output << a.ptr[i];
return output;
}
any help would be appreciated.
Implementation code for a template class must live in the header, not in the .cpp file. This is required so that other code that use your template class can "instanciate" it's code based on the template parameter.
So just move all your code from your .cpp to your .h and you're good to go.
See code below. There's something wrong with it, because the linker is complaining it can't find the Memory's functions, but I can't figure out why.
memory.h
#pragma once
#include "includes.h" //it just includes other strandard headers.
class MemoryUnit
{
public:
MemoryUnit() {}
virtual int getValue() = 0;
virtual int getSize() = 0;
virtual void setValue(int) = 0;
virtual ~MemoryUnit() {};
};
class Byte : public MemoryUnit
{
int value;
public:
static int size;
Byte(int byte) :value(byte) {};
int getSize() { return size; }
int getValue() { return value; };
void setValue(int byte) { value = byte; }
~Byte() {};
};
namespace Memory
{
extern int size;
extern MemoryUnit** map;
void checkAddress(int address);
int read(int adress);
MemoryUnit* getOperation(int address);
void write(int adress, MemoryUnit* data);
void writeByte(int adress, int data);
}
memory.cpp
#include "includes.h"
#include "memory.h"
#include "simulator.h" // it contains only externed constants.
namespace Memory
{
int size = 0;
MemoryUnit** map = NULL;
inline MemoryUnit* getOperation(int address)
{
return map[address];
}
inline void checkAddress(int address)
{
if (address < 0 || address >= MAX_MEMORY_SIZE)
throw std::out_of_range("Invalid memory address.");
}
inline int read(int address)
{
checkAddress(address);
return map[address]->getValue();
}
inline void write(int address, MemoryUnit* data)
{
checkAddress(address);
delete map[address];
map[address] = data;
}
inline void writeByte(int address, int data)
{
checkAddress(address);
map[address]->setValue(data);
}
}
Everywhere the class/namespace memory.h declares is includes memory.h. Is here anything wrong in the code below?
Edit:
I'm using Visual Studio 2015.
Errors I got when building the project:
LNK1120 5 unresolved externals simulator.exe
LNK2019 unresolved external symbol "void __cdecl Memory::writeByte(int,int)" referenced in function "void __cdecl ALU::setFlags(int)" alu.obj
LNK2001 unresolved external symbol "void __cdecl Memory::writeByte(int,int)" cu.obj
LNK2019 unresolved external symbol "class MemoryUnit * __cdecl Memory::getOperation(int)" referenced in function "void __cdecl CU::run(void)" cu.obj
LNK2001 unresolved external symbol "void __cdecl Memory::writeByte(int,int)" helpers.obj
LNK2019 unresolved external symbol "void __cdecl Memory::write(int,class MemoryUnit *)" referenced in function "void __cdecl readProgramCommands(void)" helpers.obj
LNK2001 unresolved external symbol "public: virtual int __thiscall MemoryPointer::getValue(void)" helpers.obj
LNK2001 unresolved external symbol "public: virtual int __thiscall IndirectMemoryPointer::getAddress(void)" helpers.obj
LNK2001 unresolved external symbol "void __cdecl Memory::writeByte(int,int)" main.obj
alu.h and alu.cpp for the first error:
//alu.h
#pragma once
#include "includes.h"
#include "operation.h"
namespace ALU
{
int operation(Operation* op);
void setFlags(int result);
}
//alu.cpp
#include "includes.h"
#include "simulator.h"
#include "alu.h"
#include "memory.h"
#include "operation.h"
namespace ALU
{
int operation(Operation* operation)
{
// ...
setFlags(result);
return result;
}
inline void setFlags(int result)
{
Memory::writeByte(FLAG_Z, result == 0);
// ...
}
}
You need to put the inline function definition inside your header file (they both must appear in every translation unit where they are used), you can separate declaration and definition but both must be in the header file. Also they must be declared as inline.
N4140 dcl.fct.spec 7.1.2.4
An inline function shall be defined in every translation unit in which it is odr-used and shall have exactly
the same definition in every case (3.2). [ Note: A call to the inline function may be encountered before its
definition appears in the translation unit. —end note ] If the definition of a function appears in a translation
unit before its first declaration as inline, the program is ill-formed.
When you're using inline functions or methods, their definitions should be visible for every source unit that uses them. You defined your inline functions in Memory.cpp, that's why you get 'unresolved' linker error.
To fix your problem you can:
Remove inline modifier and keep functions definitions in Memory.cpp.
Keep inline modifier but move functions definitions to Memory.h.
I wrote a simple class which manages the current execution session. Therefore, I decided to use a singleton pattern but the compilation crashes at linked step. This is the error:
error LNK2005: "class Session * session" (?session##3PAVSession##A) already defined in ClientTsFrm.obj
(...)client\FrmSaveChat.obj TeamTranslate
error LNK2005: "class Session * session" (?session##3PAVSession##A) already defined in ClientTsFrm.obj
(...)client\Login.obj TeamTranslate
error LNK2019: unresolved external symbol "protected: __thiscall Session::Session(void)" (??0Session##IAE#XZ)
referenced in function "public: static class Session * __cdecl Session::Instance(void)" (?Instance#Session##SAPAV1#XZ)
(...)client\Session.obj TeamTranslate
error LNK2001: unresolved external symbol "private: static char const * const Session::_nick" (?_nick#Session##0PBDB)
(...)client\Session.obj TeamTranslate
error LNK2001: unresolved external symbol "private: static char const * const Session::_service" (?_service#Session##0PBDB)
(...)client\Session.obj TeamTranslate
error LNK2001: unresolved external symbol "private: static char const * const Session::_serverAddress" (?_serverAddress#Session##0PBDB)
(...)client\Session.obj TeamTranslate
error LNK2001: unresolved external symbol "private: static char const * const Session::_googleAPI" (?_googleAPI#Session##0PBDB)
(...)client\Session.obj TeamTranslate
error LNK2001: unresolved external symbol "private: static char const * const Session::_language" (?_language#Session##0PBDB)
(...)client\Session.obj TeamTranslate
error LNK2001: unresolved external symbol "private: static int Session::_numbLanguageSelected" (?_numbLanguageSelected#Session##0HA)
(...)client\Session.obj TeamTranslate
error LNK2001: unresolved external symbol "private: static char const * const Session::_translationEngine" (?_translationEngine#Session##0PBDB)
(...)client\Session.obj TeamTranslate
error LNK1120: 8 unresolved externals
(...)client\bin\TeamTranslate.exe TeamTranslate
IntelliSense: identifier "wxZipStreamLink" is undefined
(..)\include\wx\zipstrm.h 417 5
session.h (singleton)
#ifndef __SESSION_H__
#define __SESSION_H__
#include <cstring>
#include <stdio.h>
class Session {
public:
static Session* Instance();
void setNick(char* nick);
const char* getNick();
void setService(char* serv);
const char* getService();
void setLanguage(char* lang);
const char* getLanguage();
const char* getServerAddress();
void setServerAddress(char *sv);
void setGoogleAPIKey(char* code);
const char* getGoogleAPIKey();
void setNumbLanguageSelected(int v);
int getNumbLanguageSelected();
const char* Session::getTranslationEngine();
void Session::setTranslationEngine(char *sv);
char* Session::getGoogleURLTranslation();
void update();
bool read();
protected:
Session();
private:
static Session* _instance;
static const char* _nick; // client nickname
static const char* _service; // service used to translation (Google, Bing,....)
static const char* _serverAddress;
static const char* _googleAPI;
static const char* _language;
static int _numbLanguageSelected;
static const char* _translationEngine;
};
#endif
Session.cpp
#include "Session.h"
Session* Session::_instance = 0;
Session* Session::Instance() {
if (_instance == 0) {
_instance = new Session;
_instance->read();
}
return _instance;
}
void Session::setGoogleAPIKey(char* code){
_googleAPI = strdup(code);
}
const char* Session::getGoogleAPIKey(){
return _googleAPI;
}
void Session::setLanguage(char* lang){
_language = strdup(lang);
}
const char* Session::getLanguage(){
return _language;
}
void Session::setNick(char* nick){
_nick = strdup(nick);
}
const char* Session::getNick(){
return _nick;
}
void Session::setService(char* serv){
_service = strdup(serv);
}
const char* Session::getService(){
return _service;
}
const char* Session::getServerAddress(){
return _serverAddress;
}
void Session::setServerAddress(char *sv){
_serverAddress = strdup(sv);
}
void Session::setNumbLanguageSelected(int v){
this->_numbLanguageSelected = v;
}
int Session::getNumbLanguageSelected(){
return _numbLanguageSelected;
}
const char* Session::getTranslationEngine(){
return _translationEngine;
}
void Session::setTranslationEngine(char* sv){
_translationEngine = strdup(sv);
}
void Session::update(){
FILE* config = fopen("conf\\config.txt", "w");
fprintf(config, "%s\n", _serverAddress);
fprintf(config, "%s\n", _nick);
fprintf(config, "%d\n", _numbLanguageSelected);
fprintf(config, "%s\n", _language);
fprintf(config, "%s", _translationEngine);
fflush(config);
fclose(config);
}
bool Session::read(){
FILE * config;
if (config = fopen("conf\\config.txt", "r"))
{
fscanf(config, "%s", _serverAddress);
fscanf(config, "%s", _nick);
fscanf(config, "%d", _numbLanguageSelected);
fscanf(config, "%s", _language);
fscanf(config, "%s", _translationEngine);
fflush(config);
fclose(config);
return true;
} else
return false;
}
char* Session::getGoogleURLTranslation(){
return "https://www.googleapis.com/language/translate/v2?key=";
}
Example about how I call the singleton:
#include "../data/Session.h"
static Session* session = Session::Instance();
Can you help me to fix the errors?
thanks in advance.
One of your headers (which you didn't show, but it is included in both "ClientTsFrm.cpp" and "FrmSaveChat.cpp") defines a variable called "session" of type Session*.
The other errors are caused by your forgetting to define most static members of Session.
I created a templated data class (CAnyData, please see its header file copy for your reference), with which I declared some variables in my another class (CConstantDataBlock, please see its header file copy for your reference). As you may see, the latter one is nearly an empty class. But when I compiled my project, the VS2008 compiler thowed the following linking errors. Would please help me figure out what's wrong with my CConstantDataBlock and/or CAnyData?
1>------ Build started: Project: Tips, Configuration: Debug Win32 ------
1>Compiling...
1>ConstantDataBlock.cpp
1>Linking...
1> Creating library F:\Tips\Debug\Tips.lib and object F:\Tips\Debug\Tips.exp
1>ConstantDataBlock.obj : error LNK2019: unresolved external symbol "public: __thiscall CAnyData<double>::~CAnyData<double>(void)" (??1?$CAnyData#N##QAE#XZ) referenced in function __unwindfunclet$??0CConstantDataBlock##QAE#XZ$0
1>ConstantDataBlock.obj : error LNK2019: unresolved external symbol "public: __thiscall CAnyData<int>::~CAnyData<int>(void)" (??1?$CAnyData#H##QAE#XZ) referenced in function __unwindfunclet$??0CConstantDataBlock##QAE#XZ$0
1>ConstantDataBlock.obj : error LNK2019: unresolved external symbol "public: __thiscall CAnyData<double>::CAnyData<double>(void)" (??0?$CAnyData#N##QAE#XZ) referenced in function "public: __thiscall CConstantDataBlock::CConstantDataBlock(void)" (??0CConstantDataBlock##QAE#XZ)
1>ConstantDataBlock.obj : error LNK2019: unresolved external symbol "public: __thiscall CAnyData<int>::CAnyData<int>(void)" (??0?$CAnyData#H##QAE#XZ) referenced in function "public: __thiscall CConstantDataBlock::CConstantDataBlock(void)" (??0CConstantDataBlock##QAE#XZ)
1>F:\Tips\Debug\Tips.exe : fatal error LNK1120: 4 unresolved externals
1>Build log was saved at "file://f:\Tips\Tips\Debug\BuildLog.htm"
1>Tips - 5 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
#pragma once
#include <string>
using namespace std;
template <class T>
class CAnyData
{
public:
CAnyData(void);
CAnyData(int nWordNumber, string sContents, T Type, int nWidth, int nPrecision);
~CAnyData(void);
// Operators
CAnyData( const CAnyData& rhs );
const CAnyData& operator = (const CAnyData& rhs);
// Must define less than relative to name objects.
bool operator<( const CAnyData& AnyData ) const;
// Compares profile's of two objects which represent CAnyData
inline bool operator ==(const CAnyData& rhs) const;
// Get properties
inline int WordNumber() const { return m_nWordNumber; }
inline const string& Contents() const { return m_sContents; }
inline const T& DataType() const { return m_Type; }
inline int Width() const { return m_nWidth; }
inline int Precision() const { return m_nPrecision; }
// Set properties
void WordNumber(int nWordNumber) const { m_nWordNumber = nWordNumber; }
void Contents(string sContents) const { m_sContents = sContents; }
void DataType(T Type) const { m_Type = Type; }
void Width(int nWidth) const { m_nWidth = nWidth; }
void Precision(int nPrecision) const { m_nPrecision = nPrecision; }
protected:
void Init(void);
protected:
int m_nWordNumber;
string m_sContents;
T m_Type;
int m_nWidth;
int m_nPrecision;
};
#pragma once
#include "AnyData.h"
// Constants block
// This block consists of 64 words to be filled with useful constants.
class CConstantDataBlock
{
public:
CConstantDataBlock(void);
~CConstantDataBlock(void);
protected:
CAnyData<int> m_nEarthEquatorialRadius;
CAnyData<int> m_nNominalSatelliteHeight;
CAnyData<double> m_dEarthCircumference;
CAnyData<double> m_dEarthInverseFlattening;
};
It seems that you do not have definitions for several of the methods of CAnyData, including the default constructor and the destructor. When you use these in your CConstantDataBlock-class, the constructor and destructor are required though.
Since CAnyData is a class-template, all definitions should be written directly into the header-file (just as you have done with all the getters and setters).
I have an very strange error: when I want to use the SocialServer::Client class from my SocialServer::Server class, the linker threw me two LNK2019 errors :
Error 1 error LNK2019: unresolved external symbol "public: void __thiscall SocialServer::Client::Handle(void)" (?Handle#Client#SocialServer##QAEXXZ) referenced in function "private: static unsigned int __stdcall SocialServer::Server::listenThread(void *)" (?listenThread#Server#SocialServer##CGIPAX#Z) C:\Users\benjamin\Documents\Visual Studio 2010\Projects\FCX Social Server\SocialServer Core\Server.obj SocialServer Core
Error 2 error LNK2019: unresolved external symbol "public: __thiscall SocialServer::Client::Client(unsigned int)" (??0Client#SocialServer##QAE#I#Z) referenced in function "private: static unsigned int __stdcall SocialServer::Server::listenThread(void *)" (?listenThread#Server#SocialServer##CGIPAX#Z) C:\Users\benjamin\Documents\Visual Studio 2010\Projects\FCX Social Server\SocialServer Core\Server.obj SocialServer Core
However , these 2 missing function are correctly implemented :
Client.h
#pragma once
#include "dll.h"
namespace SocialServer
{
class __social_class Client
{
public:
Client(SOCKET sock);
~Client();
void Handle();
private:
static unsigned __stdcall clientThread(void* value);
SOCKET _socket;
uintptr_t _thread;
unsigned int _thread_id;
};
}
Client.cpp
#pragma once
#include "Client.h"
namespace SocialServer
{
Client::Client(SOCKET socket)
{
this->_socket = socket;
}
Client::~Client()
{
}
void Client::Handle()
{
std::cout << " New client " << std::endl;
this->_thread = _beginthreadex(NULL, 0, Client::clientThread, &this->_socket, CREATE_SUSPENDED, &this->_thread_id);
ResumeThread((HANDLE)this->_thread);
}
unsigned __stdcall Client::clientThread(void* value)
{
// Some code to execute here ...
}
}
Where does the problem comes from ?
i've found the solution.
In a function that's used by _beginthreadex() (with unsigned __stdcall) , always add a return at the end.