C++ String passed to class constructor - linker errors - c++

Question

I'm a C# programmer working on a C++ project in VS 2008, trying to create an instance of an object and pass it a string as a parameter for the constructor. When I do this, I'm getting linker errors which I'm really struggling to diagnose.
The linker errors I'm getting are
2>TestMyProj.obj : error LNK2028: unresolved token (0A0002B9) "public: __thiscall myNamespace::myClass::myClass(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0myClass#myNamespace##$$FQAE#V?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std###Z) referenced in function "int __cdecl main(void)" (?main##$$HYAHXZ)
2>TestMyProj.obj : error LNK2019: unresolved external symbol "public: __thiscall myNamespace::myClass::myClass(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >)" (??0myClass#myNamespace##$$FQAE#V?$basic_string#DU?$char_traits#D#std##V?$allocator#D#2##std###Z) referenced in function "int __cdecl main(void)" (?main##$$HYAHXZ)
2>..\MyProj\TestMyProj.dll : fatal error LNK1120: 2 unresolved externals
from the project (TestMyProj) which tries to create an instance of the class. MyProj compiles fine. The code is as below:
MyProj.cpp
#include "MyProj.h"
namespace myNamespace
{
myClass::myClass(string inString){}
};
MyProj.h:
#pragma once
#include <string>
using namespace std;
namespace myNamespace
{
class myClass
{
public:
myClass::myClass(string inString);
};
}
The code where I'm trying to create an instance of the class MyClass is in another project within the same solution
TestMyProj.cpp:
#include <string>
#include "../MyProj/MyProj.h"
int main()
{
myNamespace::myClass("");
return 0;
}
I'm obviously misunderstanding something fundamental, probably about the nature of header files. I'm largely working to previously coded examples.
Can anybody point out what I'm doing wrong?

Answer 1

You need to link the projects together. In C#, when you reference a class it automatically links the assembly. With C++ you have to reference the class by including the .h file, and link the projects.
Solutions are just ways of collecting projects together and mean nothing to the compiler.
I'm a fan of statically linked libraries to be honest, but if you really want to create a dll, see https://msdn.microsoft.com/en-gb/library/ms235636.aspx and the section called "To use the functionality from the class library in the app".

Answer 2

mostly myproj.lib is not added to the library files list. in linker configuration.