Class Screen
(Figs. 23.16–23.17) represents the screen of the ATM and encapsulates all aspects of displaying output to the user. Class Screen
approximates a real ATM’s screen with a computer monitor and outputs text messages using cout
and the stream insertion operator (<<
). In this case study, we designed class Screen
to have one operation—displayMessage
. For greater flexibility in displaying messages to the Screen
, we now declare three Screen
member functions—displayMessage
, displayMessageLine
and displayDollarAmount
. The prototypes for these member functions appear in lines 12–14 of Fig. 23.16.
Figure 23.17 contains the member-function definitions for class Screen
. Line 5 #include
s the Screen
class definition. Member function displayMessage
(lines 9–12) takes a string
as an argument and prints it to the console using cout
and the stream insertion operator (<<
). The cursor stays on the same line, making this member function appropriate for displaying prompts to the user. Member function displayMessageLine
(lines 15–18) also prints a string
, but outputs a newline to move the cursor to the next line. Finally, member function displayDollarAmount
(lines 21–24) outputs a properly formatted dollar amount (e.g., $123.45
). Line 23 uses stream manipulators fixed
and setprecision
to output a value formatted with two decimal places.
18.219.249.210