Question

我参加了C ++课程的介绍，我们正在使用visual studio。我们的任务是创建一个程序，通过键入相应的字符来计算用户可以选择的不同内容。该活动向我们展示了如何在我们的代码中使用函数。我已经设置了第一个计算，但是每次运行它都会出现运行时错误＃3，当我在main中初始化circleArea时，circleArea会打印为我初始化它而不是areaCircle函数返回的值。谢谢你把我赶出去，如果这对我很重要，我很抱歉。

/// Lab6Marcelino.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <iomanip>
using namespace std;

double pi = 3.14;

// Protoypes
void showMenu(char & c);
void getRadius(double & r, bool &nega);
bool isNegative(double val);
double areaCircle(double &r);

// Main
int _tmain(int argc, _TCHAR* argv[])
{
    char menuChoice;
    double radius;
    bool negative = true;
    double circleArea;

    showMenu(menuChoice);

    if (menuChoice = 'c')
    {
        getRadius(radius, negative);
        areaCircle(radius);

        cout << "The radius is " << radius << endl
            << "The area of the circle is: " << circleArea << endl;
    }



    system("Pause");
    return 0;
}

//*************
// FUNCTIONS***
//*************

// Definition of function showMenu
// Shows Menu and asks for user choice.

void showMenu(char &menuChoice)
    {
        cout << "Enter C or c for the area of a Circle" << endl
        << "Enter T or t for the area of a Triangle" << endl
        << "Enter S or s for the area of a Sphere" << endl
        << "Enter P or p for the area of a triangular Prism" << endl
        << "Enter A or a for information about the author" << endl
        << "Enter Q or q to quit this program" << endl;
        cin >> menuChoice;
    }

// Definition of function getRadius
// Gets radius from user

void getRadius(double &r, bool &nega)
    {
        cout << "Enter the radius: ";
    cin >> r;
        isNegative(r);

        while (isNegative(r) == true)
        {
            cout << "Enter the radius: ";
            cin >> r;
            isNegative(r);
        }
    }

bool isNegative(double val)
    {
        if (val < 0)
            return true;

        if (val > 0)
            return false;
        else
        {
            cout << "Invalid input" << endl;
            return true;
        }
    }

double areaCircle(double &r)
{
    double circleArea;
    circleArea = pi * r * r;
    return circleArea;
}

Answer 1

areaCircle(radius);会返回一个值，但您不会将其分配给任何内容。然后，当您尝试将circleArea与cout一起使用时，它尚未初始化，因此您可能会遇到运行时错误。

运行时错误＃3

1 个答案: