Question

我在学校任务中遇到了这个课程的问题。该程序的目的是从用户输入计算加仑。我的问题是，我认为我的函数是错误的，当我编译时，我一直都会得到0。

#include <iostream>
#include <iomanip>
#include <string>

using namespace std;


int getdata(char, double, char);
string findGasName(char);
int computeGallons(char, double, char);
void display(string, double, double, double);


int main()
{
string gasName;
double washCost = 0;
char gasType = 'a';
double dAmountremaining = 0;
double gallons = 0;
const double washResponseunder30 = 6.95;
const double REG = 2.199;
const double UNLEAD = 2.399;
const double SUNLEAD = 2.599;
double dAmount = 0;
char washResponse = 'a';

getdata(gasType, dAmount, washResponse);

gasName = findGasName(gasType);

gallons = computeGallons(gasType, dAmount, washResponse);

display (gasName, gallons, washCost, dAmount);


system("pause");
return 0;
}

这个区域是我认为遇到麻烦的地方。我以前把int getdata函数作为一个空格但是它也没有工作。

   int getdata(char gasType, double dAmount, char washResponse) 
   {

    cout << "Enter gas type(R,U,S) ";
    toupper(gasType);
    cin >> gasType;


    while (gasType != 'R' && gasType != 'r' && gasType != 'U' && gasType != 'u' && gasType != 'S' && gasType != 's')
    {
        cout << "Enter a gas type (R,U,S) ";
        cin >> gasType;
    }

    cout << "Enter dollar Amount ";
    cin >> dAmount;

    while (dAmount < 4.95)
    {

        cout << "Please enter Amount greater than gasType " << endl;
        cin >> dAmount;
    }

    cout << "Car Wash (Y or N)";
    cin >>  washResponse;
    while (washResponse != 'Y' && washResponse != 'y' && washResponse != 'N' && washResponse != 'n')
    {
        cout << "Please enter Y for (Yes) or N for (No)";
        cin >> washResponse;
    }
    return gasType, dAmount, washResponse;
}

string findGasName(char gasType)
{
    string gasName;


    if (gasType == 'R' && gasType == 'r')
        gasName = "Regular";
    else if (gasType == 'U' && gasType == 'u')
        gasName = "Unleaded";
    else if (gasType == 'S' && gasType == 's')
        gasName = "Super";

    return gasName;
}

int computeGallons(char gasType, double dAmount, char washResponse)
{
    double washCost;
    const double washResponsewith30 = 4.95;
    double dAmountremaining = 0;
    double gallons = 0;
    const double washResponseunder30 = 6.95;
    const double REG = 2.199;
    const double UNLEAD = 2.399;
    const double SUNLEAD = 2.599;



    if (dAmount >= 30) {
        washCost = washResponsewith30;
        dAmountremaining = dAmount - washCost;

        switch (gasType)
        {
        case 'R': case 'r':
            gallons = dAmountremaining / REG;


            break;

        case 'U': case 'u':
            gallons = dAmountremaining / UNLEAD;


            break;

        case 'S': case 's':
            gallons = dAmountremaining / SUNLEAD;


            break;
        }
    }

    else if (dAmount < 30)
    {
        washCost = washResponseunder30;
        dAmountremaining = dAmount - washCost;

        switch (gasType)
        {
        case 'R': case 'r':
            gallons = dAmountremaining / REG;


            break;

        case 'U': case 'u':
            gallons = dAmountremaining / UNLEAD;


            break;

        case 'S': case 's':
            gallons = dAmountremaining / SUNLEAD;


            break;
        }

    }
    else
    {
        washCost = 0;

        switch (gasType)
        {
        case 'R': case 'r':
            gallons = dAmountremaining / REG;


            break;

        case 'U': case 'u':
            gallons = dAmountremaining / UNLEAD;


            break;

        case 'S': case 's':
            gallons = dAmountremaining / SUNLEAD;


            break;
        }
    }


    return gallons;

}


void display(string gasName, double gallons, double washCost, double dAmount)
{
    cout << "Gas type" << setw(12) << setprecision(2) << ":" << gasName << endl;
    cout << "Gallons" << setw(13) << ":" << gallons << endl;
    cout << "Car Wash" << setw(13) << ":$" << washCost << endl;
    cout << endl;
    cout << "Purchase Amount" << setw(6) << ":$" << dAmount << endl;
}

Answer 1

好吧，因为你的函数int getdata(char, double, char);没有按照你的想法做到。你想这样做。不要忘记选择最佳答案。

void getdata(char *, double*, char*);

//In your main getdata(&gasType, &dAmount, &washResponse); it should look like this

void getdata(char *gasType, double *dAmount, char *washResponse)
{

    cout << "Enter gas type(R,U,S) ";
    toupper(*gasType);
    cin >> *gasType;


    while (*gasType != 'R' && *gasType != 'r' && *gasType != 'U' && *gasType != 'u' && *gasType != 'S' && *gasType != 's')
    {
        cout << "Enter a gas type (R,U,S) ";
        cin >> *gasType;
    }

    cout << "Enter dollar Amount ";
    cin >> *dAmount;

    while (*dAmount < 4.95)
    {

        cout << "Please enter Amount greater than gasType " << endl;
        cin >> *dAmount;
    }

    cout << "Car Wash (Y or N)";
    cin >> *washResponse;
    while (*washResponse != 'Y' && *washResponse != 'y' && *washResponse != 'N' && *washResponse != 'n')
    {
        cout << "Please enter Y for (Yes) or N for (No)";
        cin >> *washResponse;
    }
}

C ++需要基本功能的指导

1 个答案: