Question

分配是编写一个程序，允许用户计算各种形状的面积和体积。不允许使用PI的一个例外的任何全局变量。

#include <iostream>
#include <iomanip>
using namespace std;

//Functions
void showMenu(int &);
double area (double, double);
double area (double);
double volume (double, double, double);
double volume (double);

int main()
{
   int choice;
   double area, volume;
   const double PI = 3.14;

   do
   {
       showMenu();
       cin >> choice;

       if (choice < 1 || choice > 5 )
       {
        cout << "Please select a valid choice of 1-5: " << endl;
        cin >> choice;
       }
    else if (choice == 1)
    {

        area = double area (double length, double width);
        cout << "The area of the rectangle is: " << endl;

    }
    else if (choice == 2)
    {

        area = double area (double radius);
        cout << "The area of the circle is: " << endl;

    }
    else if (choice == 3)
    {

        volume = double volume (double length, double width, double height);
        cout << "The volume for a box is: " << endl;

    }
    else if (choice == 4)
    {

        volume = double volume (double radius);
        cout << "The volume of a sphere is: " << endl;

    }
}
    while (choice != 5);
return 0;
}


void ShowMenu(int &choice)
{
cout << "1. Calculate the area of a rectangle";
cout << "2. Calculate the area of a circle";
cout << "3. Calculate the volume for a box";
cout << "4. Calculate the volume of a sphere";
cout << "5. Quit";
}

double area (double length, double width);
{
cout << "Enter the length: ";
cin >> length;
cout << "Enter the width: ";
cin >> width;
area = lenght * width;
}

double area (double radius);
{
cout << "Enter the radius: ";
cin >> radius;
area = PI * (radius * 2);
}

double volume (double length, double width, double height);
{
cout << "Enter the length: ";
cin >> length;
cout << "Enter the width: ";
cin >> width;
cout << "Enter the height: ";
cin >> height;
volume = length * width * height;
} 

double volume (double radius);
{
cout << "Enter the radius: ";
cin >> radius;
volume = (4/3) * PI * (radius * 3)
}

我得到的错误：

1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（20）：错误C2660：'showMenu'：函数不带0参数

1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（31）：错误C2062：输入'double'意外

1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（38）：错误C2062：输入'double'意外

1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（45）：错误C2062：输入'double'意外

1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（52）：错误C2062：输入'double'意外

1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（71）：错误C2447：'{'：缺少函数头（旧式正式列表？）
1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（80）：错误C2447：'{'：缺少函数头（旧式正式列表？）
1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（87）：错误C2447：'{'：缺少函数头（旧式正式列表？）
1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ labfour.cpp（98）：错误C2447：'{'：缺少函数头（旧式正式列表？）
1＆GT; Lab4.cpp 1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ lab4.cpp（117）：警告C4244：'='：从'double'转换为'float'，可能会丢失数据
1＆gt; c：\ users \ dylan \ documents \ visual studio 2010 \ projects \ lab4 \ lab4 \ lab4.cpp（127）：错误C2447：'{'：缺少函数头（旧式正式列表？）

Answer 1

纠正编译时错误不是一项艰巨的任务。关注错误消息并尝试找出问题所在。我将在您的代码中向您展示一些解决错误的示例。您的代码有很多错误，表明您需要在C ++中练习更多。

showMenu的声明是void showMenu(int &)，但您是通过showMenu()致电：

void showMenu(int &);
              ^^^^^
                Remove it

此外，要调用函数，您不能传递类型：

area = double area (double length, double width);
       ^^^^^^              ^^^^^^         ^^^^^^

更多，在实现函数时，不应在函数签名后放置;：

double area (double radius); <--- remove semicolon
{

Answer 2

这是错误的：

area = double area (double length, double width);

您将从area()返回值，而不是声明它。只需调用函数：

area = area(double length, double width);

area(double radius)中的计算不正确：
```
area = PI * (radius * 2);
```
那是计算周长。你应该计算面积：
```
area = PI * (radius * radius);
```
我没看到在该函数中如何识别PI。它在main()中初始化，但未传递给函数或放在全局范围内。

Answer 3

你忘记了分号：

volume = (4/3) * PI * (radius * 3)

函数声明错误：

double area (double radius);
{

应该（没有分号）

double area (double radius) {

涉及功能和类别的课程if / else if语句

3 个答案: