need 4 items to format a number
- format (fixed/scientific/general)
- width
- precision
- left/right (default is right, but suppose had used 'left' earlier
  for a string)

fixed, scientific, general:
- fixed = business format (fixed no. of decimal places)
- scientific = scientific notation (mantissa/exponent)
- general = fixed for small nos., scientific for large
- default is general
- fixed and scientific reset each other
- to return to general, resetiosflags(ios::fixed | ios::scientific)
  or cout.unsetf(ios::fixed | ios::scientific)

setw():
- only manipulator that is not sticky/persistent
- default is setw(0) = no spaces between numbers
- if number is too large, it forces columns to move over

precision():
- fixed: no. of decimal places
- scientific: no. of decimal places in mantissa
- general: total no. of digits (on this compiler)
- default is setprecision(6)

left and right:
- left and right reset each other (also internal, see below)
- default is right
- usually want 'left' for strings, then need 'right' for following number



boolalpha:
- display true and false instead of 1 and 0

what needs to be included:
- all need #include <iostream>
- manipulators with arguments need <iomanip>