Formatting C++ Output

• We have already seen how to format floating point output with the printf() function.  We can also format them with cout (although the style is a bit cryptic):

  cout.setf(ios::fixed);

  cout.setf(ios::showpoint);

  cout.precision(2);

• We can format output in other ways also (see pages 317-322)

  • Scientific notation:  cout.setf(ios::scientific);

  • Specific width:  cout.width(n); where n is the field width in number of characters

  • Right (or left) justified output:  cout.setf(ios::right); (or cout.setf(ios::left);)

• Some of these formatting commands are so useful (and used so often) that they have more convenient forms called IO Manipulators.

  • Specific width:  Use setw(n) in place of cout.width(n);

    • Example:  cout << ":" << setw(5) << x << ":" << endl;

  • Specific precision:  Use setprecision(n) in place of cout.precision(n);

    • Example:  cout << setprecision(2) << y << endl;

• To use IO Manipulators, you need to include <iomanip> in the same way as <iostream>

• There are other IO Manipulators, you can read about them here.