[英]Cant figure out how to calculate individual students totals in a loop
我对此程序有疑问。 我需要它来询问用户ID,然后询问书籍代码,然后询问书籍成本。 个人可以输入未知数量的书。 该程序需要计算出各个学生的书籍总数,然后问另一个做同样的学生。 然后,程序必须显示总计和书籍总数。 我似乎无法弄清楚该使用什么来跟踪每个学生的条目。 通过阅读有关数组的信息,我可以做到这一点。 但是我们还没有到这一点。 教授希望我们循环执行此操作。 我很迷茫,任何帮助都会很棒。
#include <iostream>
#include <iomanip>
using namespace std;
int main ()
{
//Declare Variables.
int student_id;
char book_code;
float book_cost;
float tax_amount;
float book_subtotal;
const int SENTINEL = -9999;
const double TAX = .07;
float total_book_cost;
int number_books;
int total_books_sold;
double grand_total;
//Set Variables to Zero.
number_books = 0;
total_book_cost = 0.00;
grand_total = 0.00;
//Set Decimal to two places.
cout << fixed << showpoint;
cout << setprecision(2);
//Input Data
cout<<"Please enter your Student ID, then press enter."<<endl;
cin>>student_id;
while (student_id != SENTINEL){
cout<<"Please enter your Book Code, then press enter."<<endl;
cin>>book_code;
cout<<"Please enter the cost of the book, then press enter."<<endl;
cout<<"$"; cin>>book_cost;
tax_amount = book_cost * TAX;
book_subtotal = book_cost + tax_amount;
total_book_cost += book_subtotal;
number_books++;
cout<<"\tStudent Textbook Purchases Report"<<endl;
cout<<"********************************************"<<endl;
cout<<"Student"<<"\tBook"<<"\tBook"<<"\tTax"<<"\tBook"<<endl;
cout<<"Id"<<"\tCode"<<"\tCost"<<"\tAmount"<<"\tSubtotal"<<endl;
cout<<"--------------------------------------------"<<endl;
cout<<student_id<<setw(5)<<book_code<<setw(8)<<"$"<<book_cost<<
setw(3)<<"$"<<tax_amount<<setw(4)<<"$"<<book_subtotal<<endl;
cout<<endl;
cout<<"Total number of books purchased:"<<setw(8)<<number_books<<endl;
cout<<"Total books cost including tax:"<<setw(9)<<"$"<<total_book_cost<<endl;
cout<<"Please enter your Student ID, then press enter."<<endl;
cin>>student_id;
}
grand_total += total_book_cost;
total_books_sold += number_books;
cout<<"**************************************************"<<endl;
cout<<"Grand Totals:"<<endl;
cout<<"Total number of students who purchased books:"<<endl;
cout<<"Total number of books sold:"<<endl;
cout<<"Total cost of all books and taxes:"<<setw(9)<<"$"<<grand_total<<endl;
//Can put grand totals here
system("Pause");
return 0;
}
您可以这样使用循环:
#include <iostream>
#include <iomanip>
using namespace std;
int main ()
{
//Set Decimal to two places.
cout << fixed << showpoint;
cout << setprecision(2);
int total_books_sold = 0;
double grand_total = 0.0;
const int SENTINEL = -9999;
int student_id = SENTINEL;
//Input Data
cout<<"Please enter your Student ID, then press enter."<<endl;
cin>>student_id;
while (student_id != SENTINEL){
double total_book_cost = 0.0;
int number_books = 0;
char book_code = '\0';
while (true)
{
cout<<"Please enter your Book Code, then press enter."<<endl;
cin>>book_code;
if (book_code == 'x')
break;
float book_cost;
cout<<"Please enter the cost of the book, then press enter."<<endl;
cout<<"$"; cin>>book_cost;
const double TAX = .07;
double tax_amount = book_cost * TAX;
double book_subtotal = book_cost + tax_amount;
total_book_cost += book_subtotal;
number_books++;
cout<<"\tStudent Textbook Purchases Report"<<endl;
cout<<"********************************************"<<endl;
cout<<"Student"<<"\tBook"<<"\tBook"<<"\tTax"<<"\tBook"<<endl;
cout<<"Id"<<"\tCode"<<"\tCost"<<"\tAmount"<<"\tSubtotal"<<endl;
cout<<"--------------------------------------------"<<endl;
cout<<student_id<<setw(5)<<book_code<<setw(8)<<"$"<<book_cost<<
setw(3)<<"$"<<tax_amount<<setw(4)<<"$"<<book_subtotal<<endl;
cout<<endl;
};
grand_total += total_book_cost;
total_books_sold += number_books;
cout<<"Total number of books purchased:"<<setw(8)<<number_books<<endl;
cout<<"Total books cost including tax:"<<setw(9)<<"$"<<total_book_cost<<endl;
cout<<"Please enter your Student ID, then press enter."<<endl;
cin>>student_id;
}
cout<<"**************************************************"<<endl;
cout<<"Grand Totals:"<<endl;
cout<<"Total number of students who purchased books:"<<endl;
cout<<"Total number of books sold:"<<endl;
cout<<"Total cost of all books and taxes:"<<setw(9)<<"$"<<grand_total<<endl;
//Can put grand totals here
system("Pause");
return 0;
}
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