The formatted string input functions are the opposite of the formatted
string output functions. Unlike printf and similar functions,
which generate formatted output, scanf and its friends parse
formatted input. Like the opposite functions, each accepts, as a
parameter, a template string that contains conversion specifiers. In
the case of scanf and related functions, however, the conversion
specifiers are meant to match patterns in an input string, such as
integers, floating point numbers, and character sequences, and store the
values read in variables.
