print qq{How are you?};
By default, the print function will print out
to what is called standard output, which is
normally the terminal screen. You can specify this
explicitly by saying
print STDOUT qq{How are you?};
where STDOUT is what's called the file handle
associated with standard output. There is also a
standard error:
print STDERR qq{A fatal error has occurred!};
which is normally used for reporting errors. By default,
this is also tied to the terminal screen - we will see
later how to redirect both STDOUT and STDERR
to other locations.
To get user input, you can use standard input, with an associated file handle STDIN:
print qq{Please input a number: };
my $answer = <STDIN>;
This will first print out the message, and then wait
for the user to type something. After the user presses
the return key, what was typed is captured into
the specified variable $answer. This includes the
end carriage return - if you want to remove that from
the variable, you can use chomp($answer);; this is
such a common task that often one sees
chomp(my $answer = <STDIN>);as a way to get keyboard input.