Standard Input / Output

Standard output

Functions

print

print STRING          # Print a string to standard output
print STDOUT STRING   # Print a string to standard output (same as above)
print NUMBER          # Print a number to standard output

print "Hello, world!\n";
print 42;
print;    # Prints $_ by default.

print $str;
print $arr[0];

print "one two $str_three";
print "The value of $key is $hash{$key}\n";

print <<LABEL;
...any text can go here...
LABEL

Standard input

• The string read in includes the newline character

Functions

<STDIN>

• Read from standard input

$data = <STDIN>;

Standard error

• Normally, standard error prints to the screen

Functions

print

print STDERR STRING   # Print a string to standard error
print STDERR NUMBER   # Print a number to standard error

print STDERR $err_msg;
print STDERR "Error number: $error_num";