初始化程序列表和基於範圍的函數

Question

問題： 編寫一個程序，提示用戶輸入一定數量的1,2,5,10,20,50和100美元賬單。分別查詢用戶每個尺碼的數量。

我認爲我已經完成了代碼，但問題的最後部分陳述如下： 修改程序以使用向量的初始化程序列表，並使用基於範圍的for語句來遍歷向量。注意：這些C++ 11功能可用於g ++ - 4.6和Visual Studio 2012，但可能在其他編譯器上不可用。

我不明白最後一部分問的是什麼。希望有人能在這裏指出我的正確方向。這是一個C++類，我的書沒有最新版本。

對我的代碼格式的任何批評也會很棒！

這裏是我的代碼：

#include "std_lib_facilities_3.h" 
    vector<int>bills; 
    int bill; 
    int bill_tot(){ 
     int sum = 

    1*bills[0]+2*bills[1]+5*bills[2]+10*bills[3]+20*bills[4]+50*bills[5]+100*bills[6]; 
      return sum; 
     } 
    int main() 
    try{ 
     cout << "Enter the number of One Dollar Bills you have: "; 
     cin >> bill; 
     cout << '\n'; 
     bills.push_back(bill); 
     if (bill<0) 
      error("You can't have a negative value.\n"); 

     cout << "Enter the number of Two Dollar Bills you have: "; 
     cin >> bill; 
     cout << '\n'; 
     bills.push_back(bill); 
     if (bill<0) 
      error("You can't have a negative value.\n"); 

     cout << "Enter the number of Five Dollar Bills you have: "; 
     cin >> bill; 
     cout << '\n'; 
     bills.push_back(bill); 
     if (bill<0) 
      error("You can't have a negative value.\n"); 

     cout << "Enter the number of Ten Dollar Bills you have: "; 
     cin >> bill; 
     cout << '\n'; 
     bills.push_back(bill); 
     if (bill<0) 
      error("You can't have a negative value.\n"); 

     cout << "Enter the number of Twenty Dollar Bills you have: "; 
     cin >> bill; 
     cout << '\n'; 
     bills.push_back(bill); 
     if (bill<0) 
      error("You can't have a negative value.\n"); 

     cout << "Enter the number of Fifty Dollar Bills you have: "; 
     cin >> bill; 
     cout << '\n'; 
     bills.push_back(bill); 
     if (bill<0) 
      error("You can't have a negative value.\n"); 

     cout << "Enter the number of One Hundred Dollar Bills you have: "; 
     cin >> bill; 
     cout << '\n'; 
     bills.push_back(bill); 
     if (bill<0) 
      error("You can't have a negative value.\n"); 


     cout << "You have " << bills[0] <<" One Dollar Bills.\n"; 
     cout << "You have " << bills[1] <<" Two Dollar Bills.\n"; 
     cout << "You have " << bills[2] <<" Five Dollar Bills.\n"; 
     cout << "You have " << bills[3] <<" Ten Dollar Bills.\n"; 
     cout << "You have " << bills[4] <<" Twenty Dollar Bills.\n"; 
     cout << "You have " << bills[5] <<" Fifty Dollar Bills.\n"; 
     cout << "You have " << bills[6] <<" One Hundred Dollar Bills.\n"; 
     cout << "The value of all your Dollar Bills are $" << bill_tot() << endl; 
     keep_window_open(); 
    } 
    catch (runtime_error e) { 
     cout << e.what() << '\n'; 
     keep_window_open(); 
} 

Answer 1

這說明代碼：

std::vector<int> denomination { 1,2,5,20,50,100}; // Initializer list for vector 
int sum = 0; 
int number; 
for (int bill : denomination) // range-based for loop 
{ 
    cout << "Enter the number of $" << bill << " you have: "; 
    cin >> number; 
    sum += number * bill; 
}