CPS120: Introduction to Computer ScienceCPS120: Introduction to Computer Science

Formatted I/O

Formatted Output -- CurrencyFormatted Output -- Currency

cout.setf(ios : : fixed) Print “fixed point” form, not in exponential form

cout.setf(ios : : showpoint) Says to always print the decimal point

cout.precison(2) Says to print out the two most significant decimal

digits, after rounding to this precision

Line SpacingLine Spacing In order to end a line in an output statement you may

use the new line character, \n, instead of endl. Examples:

cout << "Hello world" << '\n';cout << "Hello world" << "\n";cout << "Hello world\n";

These are practically equivalent to: cout << "Hello world" << endl;

Escape SequencesEscape Sequences

Other useful "escape sequences" (since the \ is the escape operator) are: \t to generate a tab\\ to print a backslash\' to print a single quote\" to print a double quote

Using setf and unsetfUsing setf and unsetf Each stream has format options that can be changedOPTION DESCRIPTIONleft Left-justifies the outputright Right-justifies the outputshowpoint Displays decimal point and trailing zeros for

floatsuppercase Displays e in scientific as Eshowpos Displays a leading plus signscientific Displays floating point number scientificallyfixed Displays floating-point in normal notation

Using Format OptionsUsing Format Options

Format options are set immediately prior to the COUT statement

float x = 24.0;cout << x << ‘\n’; // displays 24cout.setf(ios::showpoint);cout << x << ‘\n’; // displays 24.00000cout.unsetf(ios::showpoint);cout << x << ‘\n’; // displays 24

Using ManipulatorsUsing Manipulators You must include the <iomanip.h> header file at

the top of your program in order to use the setprecision, setw, and other manipulators. You must use place the following compiler directive at the top of your program.#include <iomanip.h>

I/O manipulators are placed directly in the output statementcout << setprecision(2) << price << ‘\n’;

Setting PrecisionSetting Precision

The setprecision manipulator allows you to limit the number of digits that are displayed when a numeric data type is displayed:

cout << setprecision(2) << price << '\n'; only allows the leading two digits of the value stored in the variable, price, to be displayed

More PreciselyMore Precisely

If the fixed format was set previously with the statement:

cout.setf(ios::fixed);then the setprecision(2) manipulator would have the effect of rounding or truncating price (and all future floating-point values in the cout stream) to the hundredths place

Field WidthField Width

The setw manipulator controls the width of the field when displaying a value. The statement:

cout << setw(10) << umEndow << endl;

sets the width of the field allocated for the variable, umEndow, to 10 characters

Formatting Numbers for OutputFormatting Numbers for Output

double price;price = 78.5;cout << "The price is $";cout << price << endl;

We want the price to be $78.50

Magic Formula for CurrencyMagic Formula for Currency

cout.setf(ios :: fixed);cout.setf(ios :: showpoint);cout.precision(2);

Formatted Output -- CurrencyFormatted Output -- Currency

cout.setf(ios : : fixed) Print “fixed point” form, not in exponential form

cout.setf(ios : : showpoint) Says to always print the decimal point

cout.precison(2) Says to print out the two most significant decimal

digits, after rounding to this precision