Q&A: Console input/output (cin/cout)

What library do you need to #include in order to display text to the screen and get input from the keyboard?

#include <iostream> is required in order to use console input (cin) and console output (cout).

What library do you need to #include to use setw and setprecision?

#include <iomanip> is required in order to use setw and setprecision commands.

What is the command to display output to the console?

cout is used to display text to the console.

cout << "Hello world!";

What is the command to display a new line to the console?

endl (end-line) is used to display new lines to the console.

cout << endl << endl << "Hello!" << endl;

What is the output stream operator?

The << sign for console output is known as the output stream operator.

How do you display string literals and variable values in the same line?

Use the << between each string literal and each variable name.

cout << "Price: $" << price << ", Weight: " << weight << " lbs" << endl;

What are the commands to get input from the keyboard?

The cin (console-in) statement is used to get input from the keyboard.
We use cin >> VARNAME; for floats, ints, and single-word strings.
We use getline( cin, VARNAME ); to get a line of text from the keyboard.
When going between cin >> VARNAME; and getline( cin, VARNAME ); we must have a cin.ignore(); in-between.

string name;
string category;
float price;
int amount;

cout << "Enter amount of item: ";
cin >> amount;

cout << "Enter price of item: $";
cin >> price;

cout << "Enter name of item: ";
cin.ignore(); // cin.ignore() required here.
getline( cin, name );

cout << "Enter category of item: ";
getline( cin, category );

What is the input srteam operator?

The >> sign for console output is known as the input stream operator.

What are escape sequences? What does \t, \n, and \" do?

When written within double quotes, "\t" adds a tab-length of spaces to the console.
When written within double quotes, "\n" adds a new-line to the console. endl is equivalent.
When written within double quotes, "\"" displays a " to the console.

How do you format currency as USD?

cout << fixed << setprecision( 2 ); // Set up formatting

float price = 9.50;
cout << "$" << price << endl;

How does the setw command work?

Code:

const int COL1 = 35, COL2 = 10, COL3 = 10;

cout << left; // Set left alignment

// Display table header
cout
  << setw( COL1 ) << "NAME"
  << setw( COL2 ) << "PRICE"
  << setw( COL3 ) << "AMOUNT"
  << endl << string( 54, '-' ) << endl;

// Display data
cout
  << setw( COL1 ) << product1_name
  << setw( COL2 ) << product1_price
  << setw( COL3 ) << product1_amount
  << endl;

cout
  << setw( COL1 ) << product2_name
  << setw( COL2 ) << product2_price
  << setw( COL3 ) << product2_amount
  << endl;

Output:

NAME                               PRICE     AMOUNT
------------------------------------------------------
Penbrand Gel Pen                   1.89      20
Graphiteco Mechanical Pencil       1.75      15