How to output a '$' character in front of my number with setw

Question

#include <iostream>
#include <iomanip>
using std::cout;
using std::fixed;
using std::showpoint;
using std::setprecision;
int main()
{
  double number = 85495.5432334;
  cout << fixed << showpoint << setprecision(2) << setw(15) << 
    "string" << setw(15) << "$" << number;
  return 0;
}

The above code outputs the $ as right justified in 15 characters, but it does not right justify the number. How do I print out the '$' character and the following number together as one item that is right justified in 15 characters without losing my showpoint/setprecision/fixed manipulations?

I tried using "$"+number.toString(), and this makes the result right justified, but this ruins the showpoint/fixed/setprecision(2) manipulations I want. How do I get it all together?

Answer 1

If your number is left aligned, just put the dollar sign first.

std::cout 
    << '$' // (the dollar sign is separate from the number)
    << std::left << std::fixed << std::setw(15) << std::setprecision(2) << number;
    << "\n";

If you wish to right-align your output, and you wish the dollar-sign to stick to your number, you have to build a temporary string. This looks a lot like before:

// build the temporary string with both the dollar sign and the number
std::ostringstream dollars;
dollars << '$' << std::fixed << std::left << std::setprecision(2) << number;

// print out the justified temporary string
std::cout << std::setw(16) << std::right << dollars.str() << "\n";

Here they are together so you can play with it:

#include <iomanip>
#include <iostream>
#include <sstream>

int main()
{
    double number = 1235495.5432334;
    
    // Left-justified
    std::cout << '[';
    {
        std::cout 
            << '$' 
            << std::left << std::fixed << std::setw(15) << std::setprecision(2) << number;
    }
    std::cout << "]\n";

    // Right-justified number field only
    std::cout << '[';
    {
        std::cout 
            << '$' 
            << std::right << std::fixed << std::setw(15) << std::setprecision(2) << number;
    }
    std::cout << "]\n";
    
    // Both right-justified
    std::cout << '[';
    {
        std::ostringstream dollars;
        dollars << '$' << std::fixed << std::left << std::setprecision(2) << number;

        std::cout << std::setw(16) << std::right << dollars.str();
    }
    std::cout << "]\n";
}

[$1235495.54     ]
[$     1235495.54]
[     $1235495.54]

Remember, many field formatting constraints (such as width) apply only to a single item being output. Building a temporary string is required when messing with specific field sizes.