Undefined reference to function in class - c++

Question

main.cpp:
#include <iostream>
#include "pokemonList.h"
void pokemonLookup();
int main() {
pokemonLookup();
return 0;
}
void pokemonLookup() {
pokemonList pL;
std::cout<<std::endl<<"What Pokemon do you want to look up? ";
std::string pokemonLookup;
std::cin>>pokemonLookup;
pL.displayPokemon(pokemonLookup);
}
pokemonList.h:
#ifndef POKEMONLIST_H
#define POKEMONLIST_H
#include <iostream>
class pokemonList
{
private:
struct pokemonTemplate {
std::string pokemonName;
std::string pokemonMoves[3];
int pokemonLevel;
int baseATK;
int baseDEF;
int baseSPATK;
int baseSPDEF;
int baseSPEED;
};
pokemonTemplate bulbasaur;
pokemonTemplate pikachu;
public:
void displayPokemon(std::string pokemon);
protected:
};
#endif // POKEMONLIST_H
pokemonList.cpp:
#include "pokemonList.h"
/*
pokemonTemplate* bulbasaur() {
bulbasaur.pokemonName = "Bulbasaur";
bulbasaur.pokemonMoves[3];
bulbasaur.pokemonLevel = 5;
bulbasaur.baseATK = 10;
bulbasaur.baseDEF = 10;
bulbasaur.baseSPATK = 10;
bulbasaur.baseSPDEF = 10;
bulbasaur.baseSPEED = 10;
}
pokemonTemplate* pikachu() {
pikachu.pokemonName = "Pikachu";
pikachu.pokemonMoves[3];
pikachu.pokemonLevel = 5;
pikachu.baseATK = 8;
pikachu.baseDEF = 10;
pikachu.baseSPATK = 12;
pikachu.baseSPDEF = 6;
pikachu.baseSPEED = 15;
}
*/
void displayPokemon(std::string pokemon) {
std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}
I realize in the pokemonList.cpp file I have a bunch of Bad Code commented out, that isn't what this question is about. When I try to compile, I get a single error in the main.cpp saying:
D:/CodeBlocks/Projects/RelearningCPlusPlus/main.cpp:15: undefined reference to `pokemonList::displayPokemon(std::string)'

Answer 1

You defined a function displayPokemon() but it isn't defined as a member function. To define it as a member function outside the class definition, you need to mention the class name:
void pokemonList::displayPokemon(std::string pokemon) {
std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}

Answer 2

it should be
void pokemonList::displayPokemon(std::string pokemon){....

Answer 3

You need to change this:
void displayPokemon(std::string pokemon) {
to this:
void pokemonList::displayPokemon(std::string pokemon) {

Answer 4

Dietmar's answer solves the problem.
But I want to add that it is better to passing argument by reference instead of passing by value with std::string pokemon in this case, thus reducing overhead. So the displayPokemon function should be:
void pokemonList:displayPokemon(std::string &pokemon) const {
std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
};
Also, remember to change the corresponding member function declaration.

Answer 5

displayPokemon function is declared as a pokemonList member function but is never defined.
This:
void displayPokemon(std::string pokemon) {
std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}
is a definition of some other function (with the same name) which is not a pokemonList class member function. To tell the compiler that this is a class pokemonList member function you must preceed its name with pokemonList::
void pokemonList::displayPokemon(std::string pokemon) {
std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}
Alternatively, you can define displayPokemon inside pokemonList class:
class pokemonList
{
private:
struct pokemonTemplate {
std::string pokemonName;
std::string pokemonMoves[3];
int pokemonLevel;
int baseATK;
int baseDEF;
int baseSPATK;
int baseSPDEF;
int baseSPEED;
};
pokemonTemplate bulbasaur;
pokemonTemplate pikachu;
public:
void displayPokemon(std::string pokemon) {
std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}
protected:
};
The difference is that in the last case the displayPokemon will be an inline function.