Sorry... I automatically made a link between binary data and hexadecimal data...
You could shift 8 bits of the unsigned long into a unsigned char one at a time, and print that character with a %c in the printf, or use putchar() or something. eg: unsigned long l = 0x38c9616e; unsigned char c; : : c = (l & 0xFF000000) >> 24; putchar(c); c = (l & 0x00FF0000) >> 16; putchar(c); c = (l & 0x0000FF00) >> 8; putchar(c); c = l & 0x000000FF; putchar(c); Is this what you were looking for? I suppose you wanted something simple, ie using printf... I'm not sure about that. printf ( "%c%c%c%c", (l & 0xFF000000) >> 24, (l & 0x00FF0000) >> 16, (l & 0x0000FF00) >> 8, l & 0x000000FF ); this might be as close as you can get. Shao Zhang wrote: > > But isn't %[Xx] just prints out as Hexdecimal? > I just tried, and it prints out something like: 38c9616e > > which consumes 8 bytes in a file. Given that unsigned long is 32 bits, > I want to use exactly 4 byte to represent it in order to save some > space. > > Thanks. > > Shao. > > Matthew Dalton [EMAIL PROTECTED] wrote: > > Try using %X or %x instead of %ld > > > > Shao Zhang wrote: > > > > > > Hi, > > > If I have an unsigned long int, instead printing out its values > > > in string using printf("%ld\n", my_var), > > > > > > I would like to print it out as a 4-byte binary data. Is there > > > any easy way to do this in C. > > > > > > Thanks. > > > Shao. > > > > > > -- > > > ____________________________________________________________________________ > > > Shao Zhang - Running Debian 2.1 ___ _ _____ > > > Department of Communications / __| |_ __ _ ___ |_ / |_ __ _ _ _ > > > __ _ > > > University of New South Wales \__ \ ' \/ _` / _ \ / /| ' \/ _` | ' \/ > > > _` | > > > Sydney, Australia |___/_||_\__,_\___/ > > > /___|_||_\__,_|_||_\__, | > > > Email: [EMAIL PROTECTED] > > > |___/ > > > _____________________________________________________________________________ > > > > > > -- > > > Unsubscribe? mail -s unsubscribe [EMAIL PROTECTED] < /dev/null > > > > -- > ____________________________________________________________________________ > Shao Zhang - Running Debian 2.1 ___ _ _____ > Department of Communications / __| |_ __ _ ___ |_ / |_ __ _ _ _ __ _ > University of New South Wales \__ \ ' \/ _` / _ \ / /| ' \/ _` | ' \/ _` | > Sydney, Australia |___/_||_\__,_\___/ /___|_||_\__,_|_||_\__, | > Email: [EMAIL PROTECTED] > |___/ > _____________________________________________________________________________