Raymond Wan wrote:
Hi all,
Hello,
I would like to write binary values to disk (as well as read them) but don't
know how to do it. In C-speak, something like this:
unsigned int foo = 42;
fwrite (&foo, sizeof (unsigned int), 1, stdout);
I think the answer involves something with pack and unpack, but I'm
completely lost as I have no experience with either. The closest I got was
my $decimal_number = 42;
my $binary_number = unpack("B32", pack("N", $decimal_number));
print "Decimal number " . $decimal_number . " is " . $binary_number .
" in binary.\n\n";
In Perl numbers and strings are interchangable so:
my $decimal_number = 42;
and
my $decimal_number = '42';
and
my $decimal_number = "42";
all do the same thing. You could also write that as:
my $decimal_number = 052; # octal representation of 42
or:
my $decimal_number = 0x2A; # hexadecimal representation of 42
or:
my $decimal_number = 0b101010; # binary representation of 42
See:
perldoc perlnumber
for more details.
The C binary number 42 is represented in Perl as a string:
my $decimal_number = "\x2A";
or:
my $decimal_number = "\052";
That is equivalent in C to:
unsigned char decimal_number = 42;
Or another way to write that in Perl is:
my $decimal_number = pack 'C', 42;
Once you have created the appropriate strings using pack() then just
print() them.
John
--
Those people who think they know everything are a great
annoyance to those of us who do. -- Isaac Asimov
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