SFML Game Development Chapter 5 Error Log

||=== Build: Debug in Book_PartV (compiler: GNU GCC Compiler) ===|
obj\Debug\Application.o||In function `ZN11ApplicationC2Ev':|
D:\SFML projects\Book_PartV\Application.cpp|19|undefined reference to `State::Context::Context(sf::RenderWindow&, ResourceHolder<sf::Texture, Textures::ID>&, ResourceHolder<sf::Font, Fonts::ID>&, Player&)'|
D:\SFML projects\Book_PartV\Application.cpp|19|undefined reference to `StateStack::StateStack(State::Context)'|
D:\SFML projects\Book_PartV\Application.cpp|31|undefined reference to `StateStack::pushState(States::ID)'|
obj\Debug\Application.o||In function `ZN11Application14registerStatesEv':|
D:\SFML projects\Book_PartV\Application.cpp|36|undefined reference to `void StateStack::registerState<TitleState>(States::ID)'|
D:\SFML projects\Book_PartV\Application.cpp|37|undefined reference to `void StateStack::registerState<MenuState>(States::ID)'|
D:\SFML projects\Book_PartV\Application.cpp|38|undefined reference to `void StateStack::registerState<GameState>(States::ID)'|
D:\SFML projects\Book_PartV\Application.cpp|39|undefined reference to `void StateStack::registerState<PauseState>(States::ID)'|
obj\Debug\Application.o||In function `ZN11Application3runEv':|
D:\SFML projects\Book_PartV\Application.cpp|53|undefined reference to `Application::TimePerFrame'|
D:\SFML projects\Book_PartV\Application.cpp|53|undefined reference to `Application::TimePerFrame'|
D:\SFML projects\Book_PartV\Application.cpp|56|undefined reference to `Application::TimePerFrame'|
D:\SFML projects\Book_PartV\Application.cpp|56|undefined reference to `Application::TimePerFrame'|
D:\SFML projects\Book_PartV\Application.cpp|59|undefined reference to `StateStack::isEmpty() const'|
D:\SFML projects\Book_PartV\Application.cpp|51|undefined reference to `Application::TimePerFrame'|
D:\SFML projects\Book_PartV\Application.cpp|51|undefined reference to `Application::TimePerFrame'|
obj\Debug\GameState.o||In function `ZN9GameStateC2ER10StateStackN5State7ContextE':|
D:\SFML projects\Book_PartV\GameState.cpp|6|undefined reference to `State::State(StateStack&, State::Context)'|
D:\SFML projects\Book_PartV\GameState.cpp|6|undefined reference to `State::~State()'|
obj\Debug\GameState.o||In function `ZN9GameState11handleEventERKN2sf5EventE':|
D:\SFML projects\Book_PartV\GameState.cpp|33|undefined reference to `State::requestStackPush(States::ID)'|
obj\Debug\GameState.o||In function `ZN9GameStateD1Ev':|
D:\SFML projects\Book_PartV\GameState.hpp|8|undefined reference to `State::~State()'|
obj\Debug\MenuState.o||In function `ZN9MenuStateC2ER10StateStackN5State7ContextE':|
D:\SFML projects\Book_PartV\MenuState.cpp|12|undefined reference to `State::State(StateStack&, State::Context)'|
D:\SFML projects\Book_PartV\MenuState.cpp|23|undefined reference to `centerOrigin(sf::Text&)'|
D:\SFML projects\Book_PartV\MenuState.cpp|30|undefined reference to `centerOrigin(sf::Text&)'|
D:\SFML projects\Book_PartV\MenuState.cpp|12|undefined reference to `State::~State()'|
obj\Debug\MenuState.o||In function `ZN9MenuState4drawEv':|
D:\SFML projects\Book_PartV\MenuState.cpp|39|undefined reference to `State::getContext() const'|
obj\Debug\MenuState.o||In function `ZN9MenuState11handleEventERKN2sf5EventE':|
D:\SFML projects\Book_PartV\MenuState.cpp|61|undefined reference to `State::requestStackPop()'|
D:\SFML projects\Book_PartV\MenuState.cpp|62|undefined reference to `State::requestStackPush(States::ID)'|
D:\SFML projects\Book_PartV\MenuState.cpp|65|undefined reference to `State::requestStackPop()'|
obj\Debug\MenuState.o||In function `ZN9MenuStateD1Ev':|
D:\SFML projects\Book_PartV\MenuState.hpp|9|undefined reference to `State::~State()'|
obj\Debug\PauseState.o||In function `ZN10PauseStateC2ER10StateStackN5State7ContextE':|
D:\SFML projects\Book_PartV\PauseState.cpp|13|undefined reference to `State::State(StateStack&, State::Context)'|
D:\SFML projects\Book_PartV\PauseState.cpp|21|undefined reference to `centerOrigin(sf::Text&)'|
D:\SFML projects\Book_PartV\PauseState.cpp|26|undefined reference to `centerOrigin(sf::Text&)'|
D:\SFML projects\Book_PartV\PauseState.cpp|13|undefined reference to `State::~State()'|
obj\Debug\PauseState.o||In function `ZN10PauseState4drawEv':|
D:\SFML projects\Book_PartV\PauseState.cpp|32|undefined reference to `State::getContext() const'|
obj\Debug\PauseState.o||In function `ZN10PauseState11handleEventERKN2sf5EventE':|
D:\SFML projects\Book_PartV\PauseState.cpp|55|undefined reference to `State::requestStateClear()'|
D:\SFML projects\Book_PartV\PauseState.cpp|56|undefined reference to `State::requestStackPush(States::ID)'|
D:\SFML projects\Book_PartV\PauseState.cpp|59|undefined reference to `State::requestStackPop()'|
obj\Debug\PauseState.o||In function `ZN10PauseStateD1Ev':|
D:\SFML projects\Book_PartV\PauseState.hpp|9|undefined reference to `State::~State()'|
obj\Debug\TitleState.o||In function `ZN10TitleStateC2ER10StateStackN5State7ContextE':|
D:\SFML projects\Book_PartV\TitleState.cpp|11|undefined reference to `State::State(StateStack&, State::Context)'|
D:\SFML projects\Book_PartV\TitleState.cpp|17|undefined reference to `centerOrigin(sf::Text&)'|
D:\SFML projects\Book_PartV\TitleState.cpp|11|undefined reference to `State::~State()'|
obj\Debug\TitleState.o||In function `ZN10TitleState4drawEv':|
D:\SFML projects\Book_PartV\TitleState.cpp|23|undefined reference to `State::getContext() const'|
obj\Debug\TitleState.o||In function `ZN10TitleState11handleEventERKN2sf5EventE':|
D:\SFML projects\Book_PartV\TitleState.cpp|34|undefined reference to `State::requestStackPop()'|
D:\SFML projects\Book_PartV\TitleState.cpp|35|undefined reference to `State::requestStackPush(States::ID)'|
obj\Debug\TitleState.o||In function `ZN10TitleStateD1Ev':|
D:\SFML projects\Book_PartV\TitleState.hpp|9|undefined reference to `State::~State()'|
||=== Build failed: 43 error(s), 0 warning(s) (0 minute(s), 6 second(s)) ===|