C ++没有适当的默认构造函数 [英] C++ no appropriate default constructor available

问题描述

我有一些C＃的经验，但C ++语法和程序构造产生一些问题。
我使用Visual C ++ 2008.首先为什么会出现这个错误：

1> ...... \\ \\ Form1.h（104）：错误C2512：
'Cargame :: Car'：没有适当的默认构造函数

其次，为什么这条线不可能？ // System :: Drawing :: Color color;

错误C3265：不能在非托管'Car' / p>

Form1.h包含：

  namespace Cargame {
 using namespaces bla bla bla 
 
 class Car; 
 
 public ref class Form1：public System :: Windows :: Forms :: Form 
 {
 public：
 Form1（void）
 {
 InitializeComponent（）; 
} 
汽车* 
 
 protected：
〜Form1（）
 {
 if（components）
 {delete components; } 
} 
 
更多的自动生成代码
 
 private：System :: Void Form1_Load（System :: Object ^ sender，System :: EventArgs ^ e）{ 
 panel1-> BackColor = System :: Drawing :: Color :: Green; 
 car = new Car（）; 
 // car-> draw（）; 
} 
}; 
} 
  

Car.h的内容：

  class Car 
 {
 private：
 int speed; 
 // System :: Drawing :: Color color; 
 
 public：
 Car（）; 
}; 
  

Car.cpp的内容

  #includestdafx.h
 #includeCar.h
 #includeForm1.h
 #include< math.h> 
 
 // extern TForm1 * Form1; 
 
 Car :: Car（）
 {
 speed = 0; 
} 
 
 void Car :: draw（）
 {
 //实现
} 
  pre> 
 
解决方案
非托管代码错误是因为你声明了一个非托管指针。
 
 
 
尝试 Car ^ car 我认为这是正确的语法。
 
 
 
将您的类定义为 ref class Car  
 
I have some experience with C# but C++ syntax and program construction makes some problems.
I am using Visual C++ 2008. Firstly why is there this error?: 

  
1>......\Form1.h(104) : error C2512:
  'Cargame::Car' : no appropriate default constructor available
Secondly, why is not this line possible? //System::Drawing::Color color;

  
error C3265: cannot declare a managed 'color' in an unmanaged 'Car'
Form1.h contains:
namespace Cargame {
    using namespaces bla bla bla

    class Car;

    public ref class Form1 : public System::Windows::Forms::Form
    {
    public:
        Form1(void)
        {
            InitializeComponent();
        }
    Car* car;

        protected:
    ~Form1()
    {
        if (components)
        { delete components; }
    }

SOME MORE AUTOMATICALLY GENERATED CODE

    private: System::Void Form1_Load(System::Object^  sender, System::EventArgs^  e) {
                 panel1->BackColor = System::Drawing::Color::Green;
                 car = new Car();
                 //car->draw();
             }
    };
}
Contents of Car.h:
class Car
{
private:
        int speed;
        //System::Drawing::Color color;

public:
        Car();
};
Contents of Car.cpp
#include "stdafx.h"
#include "Car.h"
#include "Form1.h"
#include <math.h>

//extern TForm1 *Form1;

Car::Car()
{
        speed = 0;
}

void Car::draw()
{
//implementation
}

解决方案
The unmanaged code error is because you declared a unmanaged pointer, I think.

Try Car ^ car I think that is the right syntax.

And you need to define your class as ref class Car 

                        
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