jhumphreys:

Well, it works, but I'm not really a fan of the use of the <=> operator, though it's certainly clever.</opinion>

Also, you're brute forcing things by doing the repetitive work yourself instead of having the computer do it. For example, you could do it like:

#!/usr/bin/perl             
#dectobin3.pl               
use warnings;
use strict;
   
print "Enter a decimal number, less than 256, to be converted to a bin
+ary number: ";
   
chomp(my $dec = <STDIN>);
my @bits = map { ($dec & 1<<$_)  <=> 0 } reverse 0 .. 7;
print "Bits=",join("", @bits), "\n";
[download]

That way, you can use it for larger numbers without the tedious copy, paste, edit cycle. Generally, whenever you start typing something like $bit_1, $bit_2, etc., it's time to consider using an array.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

roboticus, thanks for the reply--very useful! Am slowly working my way through intro Perl text by Cozens, so haven't learned map or join yet. But I like the array and the use of reverse you recommend.

Best,

J.

jhumphreys:

Sorry, I was a bit too idiomatic there. I probably should've suggested something more like:

my @bits;
for (128 64 32 16 8 4 2 1) {
    push @bits, ($dec & $_)  <=> 0;
}
[download]

Basically, I saw the wall of:

my $dec_a = $dec & 128;
my $dec_b = $dec &  64;
my $dec_c = $dec &  32;
my $dec_d = $dec &  16;
my $dec_e = $dec &   8;
my $dec_f = $dec &   4;
my $dec_g = $dec &   2;
my $dec_h = $dec &   1;
[download]

and thought to myself that really a loop was needed.

...roboticus

When your only tool is a hammer, all problems look like your thumb.

use warnings;
use strict;

print "Enter a decimal number, less than 256, to be converted to a bin
+ary number: ";

chomp(my $dec = <STDIN>);

printf "%08b\n", $dec;
[download]

See also the FAQ:

perldoc -q convert
[download]

But, yours is an interesting use of the <=> operator.

Toolic, thanks; and agreed, I just haven't learned the printf operator yet. (Slowly working my way through intro text by Cozens.)

Best,

J.

Unfortunately, this is alot easier.

First of all, you could use some loop starting with multiplying a variable by 2, like this:

my $bit = 256;
for (1..8) {
 $bit /= 2;
 print $dec & $bit;
}
[download]

Secondly, you can just use pack and unpack instead: print unpack ("B8", (pack "c",$dec)); Explanation: pack the number as a signed char value (0..255) in a byse sequence and unpack as 8 bits.

aitap, thanks for your reply. Am slowly working my way through intro Perl text by Cozens and pack and unpack are coming up. Will study your reply after I learn these.

Best,

J.

Hi,

Others have given you good advice on how to do it.

My two Ps worth concerns the stupidity of the users, never under estimate it.

Always check that they have entered the sort of value you require, a number under 256, and deal with anything else.

It may not matter on this little script, but it is good practise to get into.

J.C.

J.C.-

Thanks for the advice; will apply it.

Best,

J.