Question

我有一些C ++经验。我写了以下代码;

#include <iostream>
using namespace std;

double mass_H;
double mass_S;
double Mass;
double S_Space;
double H2S_Conc;
double Conc;



// calculates the molecular mass of H2S, given the molecular mass of each element
void Molecular_Mass()
{
    Mass = ((2*mass_H)+(mass_S));
}

void H2S_Concentration()
{

    Conc = H2S_Conc/100;
    //c = H2S_Conc/1000000;
}


int main()
{

    cout << "Welcome to the H2S conversion .\n";
    cout << "Please enter molecular mass of Hydrogen: "<<endl;          // enter mass of hydrogen
    cin >> mass_H;
    cout << "Please enter molecular mass of Sulphur: " << endl;         // eneter mass of sulpher
    cin >> mass_S;

    Molecular_Mass();
    H2S_Concentration();                                                  // call molecular mass function
    S_Space = 22.41;  //Nm^3/kmol
    H2S_Conc = 292; // ppm v/v

    cout << "Molecular mass of H2S is: " << Mass << "kg/kmol"<< endl;
    cout << "Standard space occupied by a kmol at 0 degrees and 1 atm is: "<< S_Space << "Nm^3/kmol" <<  endl;
    cout << "H2S concentration is: " << H2S_Conc << "parts per million, which is a real concentration of: " << Conc <<endl;

问题是当我编译并运行时，我的Conc值为0.我正在划分两个双打，我认为这不是问题。

我看过谷歌，我尝试使用浮动但是也没有用。

任何人都可以告诉我为什么它会返回零

p.s忽略我剩下的糟糕代码;）

Answer 1

在这两行之后致电H2S_Concentration()： -

S_Space = 22.41;  //Nm^3/kmol
H2S_Conc = 292; // ppm v/v

Answer 2

它正在采用其默认初始化值[l.split() for l in finallist]，因为在调用函数之前没有为其赋值。

这应该有效：

编辑：正如πάντα ῥεῖ所建议的，并且由于您在运行时对其值进行硬编码而不更改或不会更改这些值，因此建议将这两个变量设置为常量，并使用所需的值对其进行初始化，如下所示：：

#include <iostream>
using namespace std;

// ..  
int main()
{
    // ..
    S_Space = 22.41;  //Nm^3/kmol
    H2S_Conc = 292; // ppm v/v

    // ..
    H2S_Concentration(); // call molecular mass function here

    //..
    return 0;
}

Answer 3

错误已得到解答，但您可以稍微编辑一下代码。例如：

float H2S_Concentration()
{

    return H2S_Conc/100;
    //c = H2S_Conc/1000000;
}

然后在主

S_Space = 22.41;  //Nm^3/kmol
H2S_Conc = 292; // ppm v/v
Molecular_Mass();
Conc = H2S_Concentration();

用C ++划分两个双数

3 个答案: