Text input and output
To make use of the input and output facilities described here, the
header file for the type iostream
and associated operators must be
included by using the compiler directive:
#include <iostream> using namespace std;
The input stream cin
and the extraction operator
(>>
) are used for reading data from the keyboard and assigning
it to variables. cin
and cout
(see below) are
pre-defined variables of type iostream
. The >>
and
<<
operators, when associated with cin
and cout
,
are examples of user-defined operators, as discussed in section
6.
cin >> v;
Data typed at the keyboard followed by the
return or enter key is assigned to the variable v
.
cin >> v1 >> v2;
The value of more than one variable can be entered by typing their values on the same line, separated by spaces and followed by a return, or on separate lines.
A statement to print the value of a variable or a string of
characters (set of characters enclosed by double quotes) to the
screen begins with cout
, followed by the insertion
operator (<<
). The data to be printed follows the insertion
operator.
cout << "text to be printed"; cout << v; cout << endl;
The symbol endl
is called a stream manipulator and
moves the cursor to a new line. It is an abbreviation for
end of line.
Strings of characters and the values of variables can be printed on the same line by the repeated use of the insertion operator.
int total = 12; cout << "The sum is " << total << endl;
prints out
The sum is 12
and then moves the cursor to a new line.