Linker complains it cannot find existing methods (C++)

Question

I have a method defined in a header file and declared in a source file. When I call the method, the linker throws an error saying it can't find the error.

Error 1 error LNK2019: unresolved external symbol "public: class Chunk * __thiscall World::getChunk(short,short)" (?getChunk@World@@QAEPAVChunk@@FF@Z) referenced in function _main

Error 2 error LNK1120: 1 unresolved externals

World.h:

#pragma once
#include <map>
#include <vector>
#include "Chunk.h"

class World {
public:
    World();
    ~World();
    void generateChunk(short x, short z);
    inline Chunk* getChunk(short x, short z);
private:
    std::vector< std::vector<Chunk*> > loadedChunks;
};

World.cpp:

#include "World.h"
#include <iostream>

World::World() : loadedChunks(1, std::vector<Chunk*>(1)) {}

World::~World() {
    for(unsigned short x = loadedChunks.size(); x > 0; --x)
        for(unsigned short z = loadedChunks[x].size(); z > 0; --z) {
            std::cout << "Destructed" << std::endl;
            delete loadedChunks[x][z];
        }
}

void World::generateChunk(short x, short z) {
    Chunk chunk(x, z);
    delete loadedChunks[x][z];
    chunk.generate();
    loadedChunks[x][z] = &chunk;
}

Chunk* World::getChunk(short x, short z) {
    return loadedChunks[x][z];
}

Later when I run:

World world;
world.generateChunk(0, 0);
world.getChunk(0, 0);

It won't compile / link with the above mentioned error messages.

Alok Save · Accepted Answer · 2013-07-28 16:02:08Z

3

You must include the function definition in the header file since you marked it as inline.

inline Chunk* getChunk(short x, short z);

answered Jul 28, 2013 at 16:02

Alok Save

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5 Comments

Jeroen Over a year ago

I don't quite understand, it is defined in the header file.

Alok Save Over a year ago

@Binero: The code you have shown, defines it in World.cpp, it should be defined in World.h.

Jeroen Over a year ago

So when I make inline methods they should be defined in the same file as the declaration? :O

Alok Save Over a year ago

@Binero: Yes, ofcourse! With inline you tell the compiler to substitute the function call with it's body during compilation. Since each TU is compiled separately unless the compiler sees the definition it cannot perform the substitution.

Jeroen Over a year ago

Never knew that. I have in the same application multiple instances where this is not the case, and it still works. :o

Andreas Florath · Accepted Answer · 2013-07-28 16:08:19Z

2

getChunk() is defined inline - therefore the linker will not find it.

(Edit / Added). This fix should do:

inline Chunk* getChunk(short x, short z) {
    return loadedChunks[x][z];
}

and remove the implementation from the cpp file.

edited Jul 28, 2013 at 16:08

answered Jul 28, 2013 at 16:02

Andreas Florath

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2 Comments

Jeroen Over a year ago

How do I fix it without removing it's 'inlinyness'?

Andreas Florath Over a year ago

Copy the implementation into the header.

Community · Accepted Answer · 2017-05-23 12:20:25Z

1

Already answered here: inline function linker error

You must declare the body in the header because the compiler must know what it is inliling

edited May 23, 2017 at 12:20

CommunityBot

11 silver badge

answered Jul 28, 2013 at 16:07

Caian

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