binary for 'printf' routines

cleopard · 08-21-2008, 01:40 PM

This is a quick question: is '%b' a valid conversion to use in any of the 'printf' routines for binary data? I did some searching through old posts in this site and found some that said it is, though internet searching outside this site, as well as books I've looked at (both recent and not so recent) don't seem to turn up that conclusion.

ophirg · 08-21-2008, 01:59 PM

i don't think so
the man pages doesn't mention it and "gcc -Wall" says:
warning: unknown conversion type character ‘b’ in format

look in "man 3 printf"
all the options should be there.

ta0kira · 08-21-2008, 04:34 PM

It's probably better to just write(STDOUT_FILENO, data, size);, making sure to fflush(stdout); before the binary output.
ta0kira

PS The option you'd be looking for, if it was available, would just be a size specification for %s since otherwise the data's size isn't known. %s prints verbatim up to the first null byte, so all you're really looking for is printing of said null bytes, in which case nothing exists to delimit the data.

Hko · 08-21-2008, 07:04 PM

I may be wrong, but I thought the OP was asking for a format specifier to output things like: 11010101

ta0kira · 08-21-2008, 09:23 PM

That would make a lot more sense.
ta0kira

PS What doesn't make sense is that strtol can have 35 bases and printf can only use 3.

Hko · 08-22-2008, 05:32 AM

Quote:

Originally Posted by ta0kira

PS What doesn't make sense is that strtol can have 35 bases and printf can only use 3.

Good point. Though for printf there are already 22 letters used as conversion specifiers, so 35 would be too much for printf. But certainly enough left some of the more useful ones...

ta0kira · 08-22-2008, 07:36 AM

I was thinking something more along the lines of %^2b to specify e.g. base-2.
ta0kira