Allasso:

You can use the pack function to create a binary value in a scalar variable, and then write it to the output file. Be sure to use binmode on the file handle so that it won't modify the binary values you send. Something like:

use strict;
use warnings;
my $foo = 12345;
$foo = pack "l", $foo;
open my $FH, '>', "foo.bin";
binmode($FH);
print $FH $foo;
close $FH;
[download]

...roboticus

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

You probably are aware of this but "32-bit integer" could mean different things.

It could be either signed or unsigned or you may want (for networking purposes) use a different endianess (is that a word?) than the one your architecture uses.

Happily pack provides "l", "L", ,"N", and "V" to cater for all your needs as long as you know what you need.

Just to add a little "decoration" to roboticus' answer :) - you might also want to display a string representation of what you're saving, i.e.

printf STDERR "0x%08x\n", $integer;
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-- 
Education is not the filling of a pail, but the lighting of a fire.
 -- W. B. Yeats

thanks for the usual great help, dear monks.

I don't think binmode is necessary on a unix machine.

Now maybe someone can tell me how I reply to my original post, without branching off someone else's...

BTW, that "three two" was supposed to be "two four" :-)

Allasso:

While it's true that binmode isn't required on a unix box, nowhere in the OP did you mention unix. Using binmode can help portability, so I mentioned because you (or a reader solving a similar problem) might have been using Windows or other OS that may need it.

As for replying to your own node, I see that the "Comment on" link is below the update section, so I imagine that you'd just click it as for any other node. (Not intending to be snarky, I almost missed it when I looked for it too. I was expecting it to be above the update stuff.)

...roboticus

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

...as usual, I look and look and look, and then I find the answer just seconds after I post.

disregard the thing about replying to the op :-)

(I tried posting this this morning but lost internet...)