I use mac vscode, and try to run the following file. When the error message pops up, the phrases are partially strange and not meaningful. Is there a way to change setting of vscode so that the output of my error message becomes normal again, something like Parent.class, Parent.h ... instead of Zn3_Parent...?
Below is the code I run:
#include <iostream>
using namespace std;
class Parent {
public :
virtual int func () = 0;
virtual ~Parent();
};
class Child : public Parent {
public :
int data;
Child (int k) {
data = k;
}
int func() { // virtual function
cout<<"Returning square of 10\n";
return 10*10;
}
void Display () {
cout<<data<<"\n";
}
~ Child() {
cout<<"Overridden Parents Destructor \n";
}
};
int main() {
Child a(10);
a.Display();
//cout << "asdf";
return 1;
}
And the output I get:
Undefined symbols for architecture x86_64:
"__ZN6ParentD2Ev", referenced from:
__ZN5ChildD1Ev in ccn2pmId.o
"__ZTI6Parent", referenced from:
__ZTI5Child in ccn2pmId.o
"__ZTV6Parent", referenced from:
__ZN6ParentC2Ev in ccn2pmId.o
NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
collect2: error: ld returned 1 exit status
I don't want those things like __ZN6, ZTI6, ZTV6.
Related
I have a pure virtual function defined in a class as below:
template <typename T>
class PositioningMethod {
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals) = 0;
};
and implementing it in ParticleFilter as below:
class ParticleFilter:public PositioningMethod<T> {
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals) {
/*Some code and return*/
return ApproximatePosition::from(xxxx, xxxx, xxxx());
}
};
but getting below errors:
"ParticleFilter<KnownBluetoothBeacon<CartesianLocation>, RadioProximity<BluetoothBeacon>
>::getPosition(std::__1::list<RadioProximity<BluetoothBeacon>*, std::__1::allocator<RadioProximity<BluetoothBeacon>*> >&)", referenced from:
vtable for RadioProximityParticleFilter in lib.a(RadioProximityParticleFilter.o)
"ParticleFilter<KnownBluetoothBeacon<CartesianLocation>, RadioProximity<BluetoothBeacon>
>::ParticleFilter(std::__1::list<KnownBluetoothBeacon<CartesianLocation>, std::__1::allocator<KnownBluetoothBeacon<CartesianLocation> > >&, double)", referenced from:
RadioProximityParticleFilter::RadioProximityParticleFilter(std::__1::list<KnownBluetoothBeacon<CartesianLocation>, std::__1::allocator<KnownBluetoothBeacon<CartesianLocation> > >&, double) in lib.a(RadioProximityParticleFilter.o)
ld: symbol(s) not found for architecture arm64
I know vtable error generally occurs on non-implementing pure virtual functions, but in my case it is same. Any idea where I may be wrong?
Note: The above errors I am getting while integrating my C++ code with objective C in iOS. While in C++ its working fine
This below line is causing the errors in ViewController.mm:
RadioProximityParticleFilter *obj = new RadioProximityParticleFilter (*asList,50);
I completed your code to use it in my MS VS 2013 test project, and it just works - here is the full listing:
#include <iostream>
#include <list>
using namespace std;
class ApproximatePosition
{
public:
static ApproximatePosition *from( int a, int b, int c)
{
cout << "from called." << endl;
return NULL;
}
};
class ListElem{};
template <typename T>
class PositioningMethod
{
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals) = 0;
};
template <typename T>
class ParticleFilter :public PositioningMethod<T>
{
public:
virtual ApproximatePosition *getPosition(std::list<T*> &observedRadioSignals)
{
/*dummy input and return*/
int a = 0, b = 0, c = 0;
cout << "getPosition called." << endl;
return ApproximatePosition::from( a, b, c );// xxxx, xxxx, xxxx());
}
};
int main()
{
PositioningMethod<ListElem> *pm = new ParticleFilter<ListElem>();
std::list<ListElem*> l;
pm->getPosition( l );
}
The output is:
getPosition called.
from called.
I do not understand why I cannot use a public const static member of a class in the initializer list of a map (probably any container). As I understand it "MyClass::A" is an rvalue, it seems like it should be the exact same as the case where I am using "THING" which is also a static const just outside of a class.
Here is the error:
Undefined symbols for architecture x86_64:
"MyClass::A", referenced from:
_main in map-380caf.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
And here is the code:
#include <iostream>
#include <map>
#include <string>
static const int THING = 1;
class MyClass {
public:
static const int A = 1;
};
int
main()
{
int a;
typedef std::map<int, std::string> MyMap;
// compiles and works fine
a = MyClass::A;
std::cout << a << std::endl;
// compiles and works fine
MyMap other_map = { {THING, "foo"} };
std::cout << other_map.size() << std::endl;
// Does not compile
MyMap my_map = { {MyClass::A, "foo"} };
std::cout << my_map.size() << std::endl;
return 0;
}
UPDATE 1:
Using clang on OS X:
Apple LLVM version 7.0.0 (clang-700.0.72)
Target: x86_64-apple-darwin14.5.0
Thread model: posix
compiler flags:
clang++ map.cc -std=c++1y
Something in the map code probably tried to take the address of a reference to your int.
The class definition here:
class MyClass {
public:
static const int A = 1;
};
does not actually create any memory for A. In order to do that you have to do in the header file:
class MyClass {
public:
static const int A;
};
and in a CPP file:
const int MyClass::A = 1;
Or I guess with the newest C++ versions you can leave the = 1 in the header and just declare the storage in the CPP file with:
const int MyClass::A;
I've been trying to solve this problem for hours and hours...
I have a header file, implementation file and a driver file.
HEADER:
class PhoneNumber
{
private:
const int MAXTEXTS;
static int live;
static int text; // number of total texts from all the phones.
string areaCode;
string exchange;
string line;
int nlive;
int ntext; // number of texts sent on this phone
public:
static int MaxPhones;
PhoneNumber();
PhoneNumber(string, string, string, int);
void inputPhoneNumber();
void displayPhoneNumber();
void sendText();
void dialNum();
int getLive();
int getText();
int getnLive();
int getnText();
static void addLive()
{
live++;
}
static void addText()
{
text++;
}
};
IMPLEMENTATION:
int PhoneNumber::getnLive()
{
return nlive;
}
int PhoneNumber::getnText()
{
return ntext;
}
int PhoneNumber::getLive()
{
return live;
}
int PhoneNumber::getText()
{
return text;
}
error message:
habins-mbp:CS2000 Habin$ g++ -o PhoneNumber PhoneNumber.cpp PhoneNumberDriver.cpp
Undefined symbols for architecture x86_64:
"PhoneNumber::live", referenced from:
PhoneNumber::getLive() in PhoneNumber-f64d4d.o
PhoneNumber::addLive() in PhoneNumber-f64d4d.o
"PhoneNumber::text", referenced from:
PhoneNumber::getText() in PhoneNumber-f64d4d.o
PhoneNumber::addText() in PhoneNumber-f64d4d.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
IF I use g++ -c, it compiles meaning that the code works. It seems like the static int live is giving me so much trouble.
Been trying to solve this for 10+ hours and to no avail. I'm about to snap my computer in half!
please help me
You should define all the static member variables in IMPLEMENTATION part.
int PhoneNumber::live;
int PhoneNumber::text;
int PhoneNumber::MaxPhones;
My code is:
class cMySingleton{
private:
static bool bInstantiated;
int mInt;
cMySingleton(){
mInt=0;
}
public:
cMySingleton(int c){
if (bInstantiated){
cout << "you can only instantiated once";
}
else {
cMySingleton();
mInt=c;
}
}
};
int main () {
cMySingleton s(5);
cMySingleton t(6);
}
The linker keeps complaining:
Undefined symbols for architecture x86_64:
"cMySingleton::bInstantiated", referenced from:
cMySingleton::cMySingleton(int) in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
What is going on? C++ novice here~~
you should initialize static field.
http://ideone.com/Y1huV
#include <iostream>
class cMySingleton{
private:
static bool bInstantiated;
int mInt;
cMySingleton(){
mInt=0;
}
public:
cMySingleton(int c){
if (bInstantiated){
std::cout << "you can only instantiated once";
}
else {
cMySingleton();
mInt=c;
}
}
};
bool cMySingleton::bInstantiated = true;
int main () {
cMySingleton s(5);
cMySingleton t(6);
}
More information you can be find here:
Static Data Member Initialization
there was also missing include and std:: around cout.
Initialize
static bool bInstantiated;
outside of cMySingleton
bool CMySingleton::bInstantiated;
Dont forget to initialize your static member outside of your class declaration in .cpp file:
bool cMySingleton::bInstantiated = false;
The following code compiles fine. but when goes to linking,
it shows following error
Undefined symbols for architecture x86_64:
"derived::counter", referenced from:
derived::getAddressCounter() in main.cpp.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status
I suspect there is something wrong with the static. but not sure why. Because once I take out the static, the code links fine. But how does static plays any role in this code?
#include <iostream>
#include <string>
struct base_result { };
struct result : public base_result {
int a;
std::string b;
};
struct base {
static base_result counter;
};
struct derived: public base {
static result counter;
result * getAddressCounter(){
counter.a = 10;
counter.b = "haha";
return &counter;
}
};
int main (){
derived d;
result * ptr;
ptr = d.getAddressCounter();
ptr->a = 20;
ptr->b = "baba";
std::cout << ptr->a << std::endl;
std::cout << ptr->b << std::endl;
return 0;
}
struct base
{
static base_result counter;
};
Only declares the static member, You also need to define it once in your cpp file.
Good Read:
What is the difference between a definition and a declaration?
In contrast to member variables which get a reserved space in every created object, static variables can't just be declared, they need to be implemented/defined too.
Just add the lines
base_result base::counter;
result derived::counter;
to your code and it will compile just fine. Those lines instructs the compiler to actually reserve space to store the static variables you declared earlier.