c++ - 预期的构造函数、析构函数或 header

Question

该程序包含三个部分:标题、类的函数和交互的主要部分。但是，它不会编译。

我不断收到响应，指出存在预期的构造函数、析构函数或类型转换。

#ifndef BOX_H
#define BOX_H

class Box 
{

private:                
    double height;
    double width;
    double length;

public:
    Box();           
    double setHeight(); 
    double setWidth();
    double setLength();
    double getVolume();
    double getSurfaceArea();    
};
#endif  

函数.cpp:

#include "Box.hpp"

/**********************************************************************
 Box:: Box
 This is the default constructor that uses the set methods to initialize each field to 1.
 * **********************************************************************/
Box::Box()
{
    height = 1;
    width = 1;
    length = 1;
}
/*
 Does anyone know what this section does? Is it another default constructor or is is it even needed?
 Box::Box(double height, double width, double length)
 {
 setHeight(height);
 setWidth(width);
 setLength(length);
 }

*/
double Box::setHeight()
{
    return height;
}

double Box::setWidth()
{
    return width;
}

double Box::setLength()
{
    return length;
}

double Box::getVolume()
{
    return height * width * length;
}

double Box::getSurfaceArea()
{
    double SurAre = 0;
    SurAre = (2 * (length * width)) + (2 * (length * height)) + (2 * (height * width));
    return SurAre;
}

main.cpp:

#include <iostream>
#include "Box.hpp"    //contains Box class declaration
using namespace std;

int main()
{
    Box object; 

    double Alength;
    double Awidth;
    double Aheight; 

    cout << "This program will calculate the area of a box.\n";
    cout << "What is the length?";
    cin >> Alength;
    cout << "What is the width?";
    cin >> Awidth;
    cout << "What is the height?";
    cin >> Aheight;

    object.setLength(Alength);                              
    if (!object.setWidth(Awidth))                               
        cout << "Invalid box width entered. \n" << endl;     
    if (!object.setHeight(Aheight))                              
        cout << "Invalid box height entered. \n" << endl;     



    cout << "Volume: " << object.getVolume() << endl; 
    cout << "Surface Area: " << object.getSurfaceArea() << endl; 
    return 0;

}

有人知道为什么吗？

Answer 1

如果你取消注释三参数构造函数，你会得到一个错误信息，因为构造函数是一个类成员，类成员必须在类内部声明，然后才能在类外部使用或定义。

添加行

Box(double height, double width, double length);

在你的类定义中，然后额外的构造函数也可以被编译。