Question

我试图创建一个程序来为我的Kerbal Space Program游戏找出Delta-V，而C ++（在Eclipse IDE中运行）似乎相信我试图调用＆＃34; log （）＆＃34;函数实际上是我引用一个未创建的函数。我非常感谢你对此事的任何帮助！

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

int main() {
    cout << "Hello. Welcome to the Kerbal Space Program Delta V Calculator. \n";
    cout << " \n";
    cout << "Note that each stage must use the same engine for this calculator.";
    cout << "\n";
    cout << "\nHow many stages make up your rocket? :";
    int stageNumber;
    cin >> stageNumber;
    //cout << "Your rocket has " << stageNumber << " stages.\n";
    cout << "\n\nStart from the bottom stage, please. ";
    //ACTUAL DELTA V CALCULATIONS
    for(int currentStage = 1; currentStage <= stageNumber; currentStage = currentStage + 1){
        cout << "What is the total mass of this stage? :";
        int totalMass;
        cin >> totalMass;
        cout << "What is the fuel mass of this stage? :";
        int fuelMass;
        cin >> fuelMass;
        cout << "\n";
        int dryMass;
        dryMass = totalMass - fuelMass;
        cout << "Your dry mass is" << dryMass << "\n";
        cout << "\n";
        cout << "Give the specific impulse of this stage's engine. \n";
        int iSP;
        cin >> iSP;
        cout << "Here is the Delta V of your rocket.\n";
        int deltaMass;
        deltaMass = totalMass/dryMass;
        int deltaV;
        deltaV = iSP * log(deltaMass);
        cout << deltaV;

        exit(0);
    }

}

Answer 1

使用数学函数时，您可能需要在数学库中进行链接。

通常在编译命令中添加-lm选项。

Answer 2

我认为您的计算要使用double（我更喜欢这里）或float变量。现在所有小数位都被截断，因为你进行整数除法。此外，您的循环不会执行多次迭代，因为调用exit(0);会终止整个程序。删除它并使用return 0;退出主要功能。由于log(int)中没有cmath，因此会出现您的错误消息。使用double也可以解决这个问题。如果您收到链接器错误，请附加链接器选项-lm。

Delta V计算器问题与对数

2 个答案: