c++ - 麻烦简单的功能

我正在编写代码来调用与力，质量和加速度方程有关的函数。这些函数被正确调用，但是输入未按应有的相乘。我对第一个函数的输出是一个疯狂的小数字，并且对第一个函数的输出始终为0。
这是我的代码。任何反馈都将非常有帮助。谢谢。

#include <iostream>
#include <cstdlib>

using namespace std;

void displayMenu();
double force(double);
double secondForce(double,double);

int main(int argc, char** argv)
{
    int menuOption;
    displayMenu();
    system("PAUSE");
    return 0;
}

void displayMenu(void)
{
    int menuOption;
    double weight, accel;
    cout << "           Main Menu" << endl;
    cout << "Enter 1 for Force calculation with acceleration = 9.8m/s^2.\n";
    cout << "Enter 2 for Force calculation with user defined acceleration.\n";
    cout << "Enter 3 to quit the program.\n";
    cin >> menuOption;
        if(menuOption==1)
        {
            cout << "Enter a mass.\n";
            cin >> weight;
            cout << "The force is ";
            cout << force(weight);
            cout << "N.";
            }
        else if(menuOption==2){
            cout << "Enter a mass.\n";
            cin >> weight;
            cout << "Enter an acceleration.\n";
            cin >> accel;
            cout << "The force is ";
            cout << secondForce(weight, accel);
            cout << "N.";
        }
}

double force(double weight)
{
    double force, mass;
    force=(mass*(9.8));
    return force;
}

double secondForce(double secondMass, double secondWeight)
{
    double secondForce, mass, acceleration;
    secondForce=(mass*acceleration);
    return secondForce;

}

最佳答案

您正在函数中使用未初始化的变量。在程序中使用这些未初始化的变量是undefined behavior。

force=(mass*(9.8)); << mass has a garbage value
secondForce=(mass*acceleration); << mass and acceleration have a garbage value

我想你打算

double force(double weight)
{
    return weight * 9.8;
}

double secondForce(double secondMass, double secondAccel)
{
   return secondMAss * secondAccel;
}

关于c++ - 麻烦简单的功能，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/33021194/