I am trying to compile my code by using make file. It seems to me that I have a bit problem in my code but it gave me no error except reference problem( referenced from:\_main in lab2-f679eb.o )

I am trying to pass the object to function by reference.

This is my general code:
In main.cpp:

```
ClassName obj
obj.functionName(obj); // passing object to the funcion

```

In other.cpp

```
 FunctionName(ClassName &obj){
 cout<<"Please enter first name:"<<endl;
 cin>>user.fname;
 cout<<"Please enter last name:"<<endl;
 cin>>user.lname;
 }

```

In header.h:

```
  Class ClassName
  {
    public:
         std::string fname;
         std::string lname;
         FunctionName(ClassName& obj);
  };

```

The big question is that, do I have a correct structure or not ? what I want to do to pass the object to function not method. When I run the code there is no error but it gave me 

```
undefined symbols for architecture x86_64:
"ClassName:: FunctionName(ClassName&)", referenced from:
 _main in lab2-f679eb.o
 ld: symbol(s) not found for architecture x86_64

```