[英]C++ forward declaration error
我有一個像這樣的錯誤
In file included from Level.hpp:12,
from main.cpp:4:
Corridor.hpp: In method `void Game::Corridor::update()':
Corridor.hpp:41: invalid use of undefined type `class Game::Level'
Corridor.hpp:13: forward declaration of `class Game::Level'
Corridor.hpp:42: invalid use of undefined type `class Game::Level'
Corridor.hpp:13: forward declaration of `class Game::Level'
Corridor.hpp:43: invalid use of undefined type `class Game::Level'
Corridor.hpp:13: forward declaration of `class Game::Level'
Corridor.hpp:44: invalid use of undefined type `class Game::Level'
Corridor.hpp:13: forward declaration of `class Game::Level'
走廊和水平......
// Corridor.hpp
#ifndef GAME_CORRIDOR_HPP
#define GAME_CORRIDOR_HPP
#include <Moot/Math.hpp>
//#include <Level.hpp>
#include <GameWindow.hpp>
namespace Game
{
class Level; // <-- LINE 13
class Corridor
{
static const unsigned int defaultLevelDepth = 800;
Moot::Math::Vector3D wp1, wp2, wp3, wp4;
Moot::Math::Vector2D sp1, sp2, sp3, sp4;
Level * p_level;
public:
Corridor(Moot::Math::Vector3D setFirstPoint, Moot::Math::Vector3D setSecondPoint)
{
wp1 = setFirstPoint;
wp2 = setSecondPoint;
wp3 = setFirstPoint;
wp3.z += defaultLevelDepth;
wp4 = setSecondPoint;
wp4.z += defaultLevelDepth;
}
void update() {
sp1 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp1); // <- LINE 41 etc.
sp2 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp2);
sp3 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp3);
sp4 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp4);
//p_level->getLevelCamera();
}
void draw()//const
{
Moot::Color tempColor;
windowInstance().graphics().drawQuad( sp1.x, sp1.y, tempColor,
sp2.x,sp2.y, tempColor,
sp3.x, sp3.y, tempColor,
sp4.x,sp4.y, tempColor, 1);
}
void setLevel(Level* setLevel) {
p_level = setLevel;
}
};
}
#endif
和
// Level.hpp
#ifndef GAME_LEVEL_HPP
#define GAME_LEVEL_HPP
#include <Moot/Forward.hpp>
#include <Moot/Window.hpp>
#include <Moot/Math.hpp>
#include <GameWindow.hpp>
#include <Camera.hpp>
#include <Corridor.hpp>
#include <Player.hpp>
#include <vector>
namespace Game
{
class Level
{
typedef Corridor* p_corridor;
typedef std::vector<p_corridor> CorridorList;
typedef CorridorList::reverse_iterator ReverseCorridorItter;
CorridorList m_map;
Camera m_camera;
Player m_player;
public:
Level()
{
m_player.setLevel(this);
// Lots of vertices being defined into m_map.
// Loop through and set camera
ReverseCorridorItter rit;
for(rit = m_map.rbegin(); rit != m_map.rend(); rit++)
(*rit)->setLevel(this);
}
~Level()
{
ReverseCorridorItter rit;
for(rit = m_map.rbegin(); rit != m_map.rend(); rit++)
delete (*rit);
m_map.clear();
}
void update()
{
// Temp delete when input and player are implimented.
if(pad[0].buttons & PAD_UP)
m_camera.updateTargetOffsets(0, -2);
if(pad[0].buttons & PAD_DOWN)
m_camera.updateTargetOffsets(0, 2);
if(pad[0].buttons & PAD_LEFT)
m_camera.updateTargetOffsets(-2, 0);
if(pad[0].buttons & PAD_RIGHT)
m_camera.updateTargetOffsets(2, 0);
m_player.update();
ReverseCorridorItter rit;
for (rit = m_map.rbegin(); rit != m_map.rend(); rit++)
(*rit)->update();
}
void draw() // const // EH!!! wtf ReverseIter isn't a member
{
m_player.draw();
ReverseCorridorItter rit;
for (rit = m_map.rbegin(); rit != m_map.rend(); rit++)
(*rit)->draw();
}
Camera& getLevelCamera() {
return m_camera;
}
};
}
#endif
據我所知,指針正在設置,但是當我嘗試從Level,BOOM訪問一個函數時!
謝謝。
PS:編譯器是gcc 2.95.2,如果這有所不同。
編輯
更新完整代碼。
你是#include
-ing Level
的完整聲明:
#include <Level.hpp>
... 然后你嘗試向前聲明Level
:
namespace Game
{
class Level;
不要這樣做。 選擇其中一個。 ( 編輯 )或者至少在完整聲明的#include
-ion之前放置前向聲明。 如果你在game_corridor.hpp
中game_corridor.hpp
只是設置指向Level
指針,那么前向聲明應該沒問題。 但是,如果您需要在HPP文件中調用Level
函數,那么您需要#include
完整的聲明。
根據您對OP的澄清編輯,您必須 #include
完整的Level
聲明,而不是嘗試使用前向聲明。
如果你轉發聲明Game::Level
那么就不要#include它。 在一個不那么相關的注釋中,使用#include "header.hpp"
,而不是#include <header.hpp>
。
根據您的更新進行編輯 :將標題Game::Corridor::update()
置於標題之外,並放入實現文件中。 這樣編譯就不需要了解Game::Level
除了它存在並且它是一個類型。
問題是Corridor不知道Level是什么,因為它不能真正#include Level.hpp,因為Level.hpp是#included Corridor.hpp。
根本問題是你正試圖#include一個源文件。 真正潛在的問題是,當您沒有將代碼分離為源文件和頭文件時,您正在使用#include
。 這是如何拆分它。 (我假設您熟悉將源文件編譯為目標文件,然后將它們鏈接到可執行文件中。)
Corridor.hpp:
#ifndef GAME_CORRIDOR_HPP
#define GAME_CORRIDOR_HPP
#include <Moot/Math.hpp>
#include <Level.hpp>
namespace Game
{
class Level;
class Corridor
{
static const unsigned int defaultLevelDepth = 800;
Moot::Math::Vector3D wp1, wp2, wp3, wp4;
Moot::Math::Vector2D sp1, sp2, sp3, sp4;
Level * p_level;
public:
Corridor(Moot::Math::Vector3D setFirstPoint, Moot::Math::Vector3D setSecondPoint);
void update();
void draw();
void setLevel(Level* setLevel);
};
}
#endif
Corridor.cpp:
#include "Corridor.hpp"
namespace Game
{
Corridor::Corridor(Moot::Math::Vector3D setFirstPoint, Moot::Math::Vector3D setSecondPoint)
{
wp1 = setFirstPoint;
wp2 = setSecondPoint;
wp3 = setFirstPoint;
wp3.z += defaultLevelDepth;
wp4 = setSecondPoint;
wp4.z += defaultLevelDepth;
}
void Corridor::update()
{
sp1 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp1);
sp2 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp2);
sp3 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp3);
sp4 = p_level->getLevelCamera().convert3DVectorWithScreenAlgorithm(wp4);
}
// and so on
}
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