Output

Chapter 3

Formatting Output with Stream Manipulators

• cout << expression or manipulator << expression or manipulator << ...;
• Expression is evaluated
• Value is printed
• A manipulator is used to format the output.
  • For example, endl, adds a line break.

setprecision(n) outputs decimal numbers with up to n decimal places.

fixed outputs floating-point numbers in a fixed decimal format.

scientific outputs floating-point numbers in scientific format.

showpoint forces output to show the decimal point and trailing zeros.

setw(n) outputs the value of an expression in a specified number of columns.

• If number of columns exceeds the number of columns required by the expression.
  • The output of the expression is right-justified.
  • Unused columns to the left are filled with spaces

setfill(ch) fills unused columns with a character.

• Example:
  cout << setfill('#');

Additional formatting tools that give you more control over your output:

• left and right manipulators
• unsetf manipulator

There are two types of manipulators: (1) with parameters (parametrized) and (2) without parameters (nonparametrized)

• Parameterized manipulators require the iomanip header (e.g., setprecision, setw, and setfill).

• Nonparametrized manipulators only require the iostream header (e.g., endl, fixed, showpoint, left, and flush)

Self-Check Questions

1. What library can be used to make our command-line output look so pretty?
2. The manipulator setprecsion() only applies to what type of numbers?
3. All the manipulators discussed apply to all the input that follows it, except for _____.