初始化列表和const引用

Question

我有一个关于初始化列表和const元素的问题。如果我声明了"const & myTimestep“，那么它就不能工作(无效的参数)，如果我删除了它，它就会工作。我错过了什么吗？非常感谢

HEADER______Solver.h____________

class Timestep; //forward declaration
class Solver {
public:
Solver(const Timestep &theTimestep)
void findSolution();
private:
const Timestep& myTimestep; //works perfectly if i remove const!
};

SOURCE______Solver.cpp_________

#include "Timestep.h"
#include "Solver.h"
Solver::Solver(const Timestep& theTimestep) : myTimestep(theTimestep)
{ }
Solver::findSolution(){
vec mesh = myTimestep.get_mesh(); //a memberfunction of Timestep
//and do more stuff
}

HEADER______Timestep.h____________

class Solver; //forward declaration
class Timestep{
public:
Timestep();
vec get_mesh(); //just returns a vector
...
}

SOURCE______Timestep.cpp_________

#include "Timestep.h"
#include "Solver.h"
Timestep::Timestep()
{
Solver mySolver(&this);
}
Timestep::get_mesh(){
return something;
}


MAIN_______main.cpp_____________
#include "Timestep.h"
#include "Solver.h"

main(){
Timestep myTimestep;
}

Answer 1

您必须将get_mesh定义为const方法，因为您在Solver中将时间步骤声明为成本变量，然后只允许调用const方法：

int get_mesh() const;

但是，您的代码中出现了各种错误，但是这样做是有效的：

class Timestep{
    public:
        Timestep();
        int get_mesh() const; //just returns a int
};

class Solver {
    public:
        Solver(const Timestep &theTimestep);
        void findSolution();
    private:
        const Timestep& myTimestep; //works perfectly if i remove const!
};

Solver::Solver(const Timestep& theTimestep) : myTimestep(theTimestep) {}

void Solver::findSolution()
{
    int mesh = myTimestep.get_mesh(); //a memberfunction of Timestep
    //and do more stuff
}


Timestep::Timestep()
{
    Solver mySolver(*this);
}

int Timestep::get_mesh() const
{
    return 0;
}


int main(){
    Timestep myTimestep;
}