Undefined reference to Class::Class/Function (Beginner in OOP) - c++

Question

I have this annoying error;
Undefined Reference to Shape::Shape(...), Shape::getName(...), Shape::getAge(...)
My Main.cpp is this
#include <iostream>
#include <string>
#include "Bit.h"
using namespace std;
int main()
{
//simple assignment
string name;
int age;
cout<<"enter name: ";
cin>>name;
cout<<"enter age: ";
cin>>age;
Shape sh(name,age); //class declaration (i think here is the problem)
cout<<endl<<"name: "<<sh.getName();
cout<<endl<<"age: "<<sh.getAge();
return 0;
}
This is the Bit.h header
#include <iostream>
#include <string>
using namespace std;
#ifndef BIT_H
#define BIT_H
//creating class
class Shape{
string newName;
int newAge;
public:
//Default Constructor
Shape();
//Overload Constructor
Shape(string n,int a);
//Destructor
~Shape();
//Accessor Functions
string getName();
int getAge();
};
And finally, this is the Bit.cpp
#include "Bit.h"
//constructors and destructor
Shape::Shape(){
newName="";
newAge=0;
}
Shape::Shape(string n, int a){
newName=name;
newAge=age;
}
Shape::~Shape(){
}
string Shape::getName(){
return newName;
}
//getters
int Shape::getAge(){
return newAge;
}
I understand, that this might be a very simple problem/error, but I have been struggling for about 2 hours.
I suppose that the error is in the declaration od "sh" object, even if I declare it like this "Shape sh();" or "Shape sh;", there are still errors.
Thanks
EDIT. GNU GCC Compiler
EDIT2. Using Code Blocks (sorry for forgetting all these)

Answer 1

You're probably not compiling Bit.cpp, but only Main.cpp.
Considering that Bit.h, Bit.cpp and Main.cpp are in the same folder, here is how you should compile it :
g++ *.cpp
It will still not compile, as in the default constructor, you're trying to initialize name, and age which both don't exist.
You probably meant newAge, and newName?
In the other Constructor, name and age also don't exist, you probably meant n, and a?