Question

main.cpp中：

#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;
}

我在pokemonList.cpp文件中发现我有一堆Bad Code被注释掉了，这不是这个问题的内容。当我尝试编译时，我在main.cpp中遇到一个错误：

D:/CodeBlocks/Projects/RelearningCPlusPlus/main.cpp:15: undefined reference to `pokemonList::displayPokemon(std::string)'

Answer 1

您定义了一个函数displayPokemon()，但未将其定义为成员函数。要将其定义为类定义之外的成员函数，您需要提及类名：

void pokemonList::displayPokemon(std::string pokemon) {
    std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}

Answer 2

应该是

void pokemonList::displayPokemon(std::string pokemon){....

Answer 3

你需要改变这个：

void displayPokemon(std::string pokemon) {

到此：

void pokemonList::displayPokemon(std::string pokemon) {

Answer 4

Dietmar的回答解决了这个问题。

但我想补充一点，最好是通过引用传递参数，而不是在这种情况下用std::string pokemon传递值，从而减少开销。所以displayPokemon函数应该是：

void pokemonList:displayPokemon(std::string &pokemon) const {
    std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
};

另外，请记住更改相应的成员函数声明。

Answer 5

displayPokemon函数被声明为pokemonList成员函数，但从未定义过。

此：

void displayPokemon(std::string pokemon) {
    std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}

是一些其他函数（具有相同名称）的定义，它不是pokemonList类成员函数。要告诉编译器这是一个类pokemonList成员函数，您必须在其名称前加上pokemonList::

void pokemonList::displayPokemon(std::string pokemon) {
    std::cout<<std::endl<<"Looking up: " + pokemon<<std::endl;
}

或者，您可以在displayPokemon类中定义pokemonList：

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:
};

不同之处在于，在最后一种情况下，displayPokemon将是内联函数。

未定义的类中函数引用

5 个答案: