Getting "error LNK2019: unresolved external symbol ... "

Question

I'm trying to get started with C++ but I keep getting this error. I know which parts of my code is generating it, but I think that at least one these parts shouldn't generate them.

I am creating a class called Text that is functioning in a way similar to the std::string class, just to experiment and get a better understanding of value semantics.

Anyhow, these are my files:

Text.h:

#ifndef TEXT
#define TEXT

class Text {
   public:
      Text(const char *str);
      Text(const Text& other);
      void operator=(const Text& other);
      ~Text();

   private:
      int size;
      char* cptr;           
};

#endif

Text.cpp:

#include "Text.h"
#include <cstring>
#include <iostream>
using namespace std;

Text::Text(const char* str) {
    size = strlen(str) + 1;
    cptr = new char[size];
    strcpy(cptr, str);
}

Text::Text(const Text& other) {
    size = other.size;
    cptr = new char[size];
    strcpy(cptr, str);
}

void Text::operator=(const Text& other){
    delete [] cptr;
    size = other.size;
    cptr = new char[size];
    strcpy(cptr, other.ctpr);
}

Text::~Text() {
    delete [] cptr;
}

Main.cpp:

#include <iostream>
#include "Text.h"
using namespace std;

Text funk(Text t) {
    // ...
    return t;
}

int main() {
    Text name("Mark");
    Text name2("Knopfler");
    name = funk(name);

    name = name2;

    return 0;
}

So what's causing the error is the function funk, and the first two lines in the main function. I get why it's complaining on the first two lines in the main function, because there are no function called "name" or "name2". But what I'm trying to do is declaring and initialize an object in one line (I'm and old Java guy :p), is this even possible in C++? I can't find anything online indicating this.

The funny thing is that this code is more or less copied from some code my lecturer executes just fine during a lecture. And he has certainly not declared any functions named "name" and "name2" either. Any reasonable explanation for this?

But why is the function funk generating this error as well? All I am doing is returning a copy of the object that I'm sending in.

Thanks in advance!

Edit: Here comes the full error messages. There are five of them. "SecondApplication" is the name of my project.

Error 1 error LNK2019: unresolved external symbol "public: __thiscall Text::Text(char const *)" (??0Text@@QAE@PBD@Z) referenced in function _main C:\Users\XXX\Documents\Visual Studio 2013\Projects\SecondApplication\SecondApplication.obj SecondApplication

---

Error 2 error LNK2019: unresolved external symbol "public: __thiscall Text::Text(class Text const &)" (??0Text@@QAE@ABV0@@Z) referenced in function "class Text __cdecl funk(class Text)" (?funk@@YA?AVText@@V1@@Z) C:\Users\XXX\Documents\Visual Studio 2013\Projects\SecondApplication\SecondApplication.obj SecondApplication

---

Error 3 error LNK2019: unresolved external symbol "public: void __thiscall Text::operator=(class Text const &)" (??4Text@@QAEXABV0@@Z) referenced in function _main C:\Users\XXX\Documents\Visual Studio 2013\Projects\SecondApplication\SecondApplication.obj SecondApplication

---

Error 4 error LNK2019: unresolved external symbol "public: __thiscall Text::~Text(void)" (??1Text@@QAE@XZ) referenced in function "class Text __cdecl funk(class Text)" (?funk@@YA?AVText@@V1@@Z) C:\Users\XXX\Documents\Visual Studio 2013\Projects\SecondApplication\SecondApplication.obj SecondApplication

---

Error 5 error LNK1120: 4 unresolved externals C:\Users\XXX\Documents\Visual Studio 2013\Projects\SecondApplication\Debug\SecondApplication.exe 1 1 SecondApplication

Answer 1

You'll get the link errors (not compilation errors) that you see if you, for instance, forget to add "Text.cpp" to your project so it doesn't get compiled and linked.

There are two errors in the code - one is in the copy constructor, and one is in the assignment operator.

Since the compiler didn't complain about the two errors, I suspect you forgot to add the file to the project.