Output to STDOUT
Perl uses the print
and printf
functions to write to standard output. Let’s look at how they
are used.
Using print for Normal Output
We’ve already used print
to display text on
standard output. Let’s expand on that usage a bit.
The print
function takes a list of strings and sends each string to standard
output in turn, without any intervening or trailing characters added.
What might not be obvious is that print
is really
just a function that takes a list of arguments, and returns a value
like any other function. In other words:
$a = print("hello ", "world", "\n");
would be another way to say hello world
. The
return value of print
is a true or false value, indicating the success of the print. The
print nearly always succeeds, unless you get some I/O error, so
$a
in this case will usually be 1.
Sometimes you’ll need to add
parentheses to print
as
shown in the example given below, especially when the first thing you
want to print starts with a left parenthesis, as in:
print (2+3),"hello"; # wrong! prints 5, ignores "hello" print ((2+3),"hello"); # right, prints 5hello print 2+3,"hello"; # also right, prints 5hello
Using printf for Formatted Output
You may wish to have a little more control over your output than
print
provides. In fact, you may be accustomed to
the formatted output of C’s
printf
function. Fear not: Perl provides a
comparable operation with the same name.
The
printf
function takes a list of arguments (enclosed in optional parentheses,
like the print
function). ...
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