向前申报问题

我认为我有向前声明的问题。我认为一个是必要的，但我不确定。

//main.cpp
#include <iostream>
#include "CalculateForces.h"
#include "ParticleBox.h"
int main(void)
{
    //g++ main.cpp ParticleBox.cpp -lgsl -lgslcblas -lm -std=c++0x
    CalculateForces* calculate_forces= new CalculateForces();
    ParticleBox* particles_box = new ParticleBox(2000,100,100,100);
    delete calculate_forces;
    delete particles_box;
    return 0;
}

CalculateForces.h是这样的:

//CalculateForces.h
//We update the forces on each particle
class ParticleBox;
class CalculateForces
{
    public:
        CalculateForces(void);
        ~CalculateForces(void);
        int UpdateForces(ParticleBox* particlebox);
        int DiscretizeSpace(float cutoff_distance);
        int LJForce(int local_index, int remote_index, ParticleBox* particlebox);               
};

最后的ParticleBox.h文件看起来像这样:

//ParticleBox.h
//This is the definition of the particlebox. We manage all the particles in this
//file
//This should be changed to a template so that we can run float and double calcs properly :D
struct Particle;
class ParticleBox
{
public:
    ParticleBox(int Num_Particles, float Box_length_x_, float Box_length_y_, float Box_length_z_);
    ~ParticleBox(void);
    int set_num_particles(int Num_Particles);
    int InitialiseUniverse(int temp,float mass);
    float Boltzmann(float temperature);
    int GenerateRandomUniquePositions(int number, float max, float min, float* rand_dim_positions);
private:
    //Array to hold particles. Each particle has its own struct
    Particle** particle_list_;
    int num_particles_;
    float box_length_x_;
    float box_length_y_;
    float box_length_z_;
    float* rand_x_positions_;
    float* rand_y_positions_;
    float* rand_z_positions_;
    float cutoff_distance_;
    float sigma_;
    float epsilon_;
};
int CalculateForces::DiscretizeSpace(float cutoff_distance, ParticleBox* particlebox)
{
    ......
    return 0;
}

我在Particle Struct的ParticleBox.h中使用了一个前向声明，我可以向类中添加一个类型为Particle*的指针。

类ParticleBox的CalculateForces.h中的forward会导致编译器错误的负载(太多的帖子，但它们以与下面相同的方式开始)。省略它只会产生一些错误:

In file included from main.cpp:3:0:
CalculateForces.h:9:20: error: ‘ParticleBox’ has not been declared
CalculateForces.h:11:50: error: ‘ParticleBox’ has not been declared
In file included from CalculateForces.cpp:3:0:
CalculateForces.h:9:20: error: ‘ParticleBox’ has not been declared
CalculateForces.h:11:50: error: ‘ParticleBox’ has not been declared
CalculateForces.cpp:12:35: error: ‘int CalculateForces::UpdateForces’ is not a static member of ‘class CalculateForces’
CalculateForces.cpp:12:35: error: ‘ParticleBox’ was not declared in this scope
CalculateForces.cpp:12:48: error: ‘particlebox’ was not declared in this scope
CalculateForces.cpp:13:1: error: expected ‘,’ or ‘;’ before ‘{’ token

我想我需要前向声明，因为我试图使用该类型作为参数?我做错了什么?

谢谢，很抱歉写了这么长一篇