Undefined symbol vtable for <class name>

[Tex08]

I did it again... after trashing the old code and trying to start simple, I receive the following error at compile (with g++, required)"

g++ main.cc
Undefined first referenced
symbol in file
vtable for Literal /var/tmp//ccBK9IR0.o
vtable for BooleanExp /var/tmp//ccBK9IR0.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status

The code I am compiling is all located in one file (lines commented in main are trying to locate errors in headers):

// Second attempt
 
#include <iostream>
 
using namespace std;
 
// Will be BooleanExp.h
 
class BooleanExp {
public:
    virtual ~BooleanExp();
 
    virtual bool GetValue();
 
protected:
    BooleanExp();
 
};
 
// Will be BooleanExp.cc
 
 BooleanExp::BooleanExp() {};
 
// Will be Literal.h
 
class Literal : public BooleanExp  {
public:
    virtual ~Literal();
 
//protected:
    Literal( bool * );
 
private:
    bool _value;
 
};
 
// Will be Literal.cc
 
Literal::Literal(bool * v) {
    _value = v;
}
 
 
 
// Will be main.cc
 
int main() {
 
//Literal * a;
//a = new Literal(0);
 
cout << "So far so good/n";
 
//delete a;
 
}
 
 

Again, any help would be greatly appreciated.

Tex

[weaknessforcats]

There is an error in this constructor:

Literal::Literal(bool * v) { 
    _value = *v;         <--- you have v which is a bool*. _value is a bool.
} 
 

Other than that everything compiles OK but the actual member functions are not found by the linker I guess because you didn't send them along.

[Tex08]

I corrected the error you had pointed out, however I still cannot compile the program. All of the code is contained in one file for now (it will be broken apart as indicated in the code). Beside the few cout statements that were added, everything list below is contained in one file, main.cc:

// Second attempt
 
#include <iostream>
 
using namespace std;
 
// Will be BooleanExp.h
 
class BooleanExp {
public:
    virtual ~BooleanExp();
 
    virtual bool GetValue();
 
protected:
    BooleanExp();
 
};
 
// Will be BooleanExp.cc
 
 BooleanExp::BooleanExp() {cout << "In BooleanExp constructor\n";};
 
// Will be Literal.h
 
class Literal : public BooleanExp  {
public:
    virtual ~Literal();
 
//protected:
    Literal( bool * );
 
private:
    bool _value;
 
};
 
// Will be Literal.cc
 
Literal::Literal(bool * v) {
    cout << "In Literal constructor\n";
    _value = *v;
};
 
 
 
// Will be main.cc
 
int main() {
 
//Literal * a;
//a = new Literal(0);
 
cout << "So far so good/n";
 
//delete a;
 
}

in which upon compiling, I received:

g++ main.cc
Undefined                       first referenced
 symbol                             in file
vtable for Literal                  /var/tmp//ccdlycaz.o
vtable for BooleanExp               /var/tmp//ccdlycaz.o
BooleanExp::~BooleanExp()           /var/tmp//ccdlycaz.o
ld: fatal: Symbol referencing errors. No output written to a.out
collect2: ld returned 1 exit status
 

Any other suggestions?

Thank you again.

[weaknessforcats]

All the code is not in your posting.

You are missing:

BooleanExp::GetValue()
BooleanExp::~BooleanExp()
Literal::~Literal()

I wrote some dummies and I got a good compiule and link.

[Tex08]

THANK YOU again...

After finding some other errors, it finally works.

Thanks again.