C++ cout list with decimals aligned using setw(x) not put_money

问题

C++ Code runs well, but currently outputting values to right but justified left and not lining up on the decimal. Can't use put_money, what am I missing?

Attempted using fprint and put_money, confirmed with classmate we're supposed to use setw(x).

#include <iostream>
#include <string>
#include <iomanip>
using namespace std;


int main()
{
const double taxRate = 0.09;
const double laborCPH = 35.0; //where CPH is Cost Per Hour
double costParts;
double costLabor;
double totalTax;
double totalDue;
string name;
double laborHours;

     cout << "What is your name? ";
     cin >> name;

     cout << "How many hours of labor needed? ";
     cin >> laborHours;

costLabor = laborHours * laborCPH;

     cout << "What was the cost of the parts and supplies? ";
     cin >> costParts;
     cout << endl << endl;


totalTax = costParts * taxRate;

totalDue = costParts + totalTax + costLabor;

     cout.precision(2);
     cout << setw(25) << left << "Customer Name " << fixed << right << internal << name << endl;
     cout << setw(25) << left << "Hours of Labor " << fixed << right << internal  << laborHours << endl;
     cout << setw(25) << left << "Cost for Labor " << fixed << right << internal  << costLabor << endl;
     cout << setw(25) << left << "Parts and Supplies " << fixed << right << internal  << costParts << endl;
     cout << setw(25) << left << "Tax " << fixed << right << internal  << totalTax << endl;
     cout << setw(25) << left << "Total Amount Due " << fixed << right << internal  << totalDue << endl;

 return 0;
}

Actual output:

What is your name? Jones
How many hours of labor needed? 4.5
What was the cost of the parts and supplies? 97


Customer Name            Jones
Hours of Labor           4.50
Cost for Labor           157.50
Parts and Supplies       97.00
Tax                      8.73
Total Amount Due         263.23

Desired output:

What is your name? Jones
How many hours of labor needed? 4.5
What was the cost of the parts and supplies? 97


Customer Name            Jones
Hours of Labor             4.50
Cost for Labor           157.50
Parts and Supplies        97.00
Tax                        8.73
Total Amount Due         263.23

回答1:

When you use std::internal to pad the rest of the space before printing, it will print all of the remaining space to the terminal. If you look closely at your output, you can see there's 25 characters before the start of your numbers (or your name if it's the first line.)

You can get around this by calculating the lengths of the strings you'll be printing and subtracting that from the setw() call, but that gets complicated for fixed-precision floats and doubles. Luckily, there's an easier way!

As Fred Larson pointed out in the comments, a great way to get around this is by adding a second setw() and std::internal after your first call to std::internal like so:

     cout.precision(2);
     cout << setw(20) << left << "Customer Name " << fixed << right << internal << setw(7) << internal << name << endl;
     cout << setw(20) << left << "Hours of Labor " << fixed << right << internal << setw(7) << internal << laborHours << endl;
     cout << setw(20) << left << "Cost for Labor " << fixed << right << internal << setw(7) << internal << costLabor << endl;
     cout << setw(20) << left << "Parts and Supplies " << fixed << right << internal << setw(7) << internal << costParts << endl;
     cout << setw(20) << left << "Tax " << fixed << right << internal << setw(7) << internal << totalTax << endl;
     cout << setw(20) << left << "Total Amount Due " << fixed << right << internal  << setw(7) << internal << totalDue << endl;

This allows the terminal to fill the output with spaces, then buffer your numbers or strings with additional spaces, and then finally print all your numbers aligned. Just be sure to give your second setw() enough space to accommodate large numbers, if you're expecting them.

Try it here!

来源：https://stackoverflow.com/questions/57828082/c-cout-list-with-decimals-aligned-using-setwx-not-put-money

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c++

decimal

cout

setw