I'm really a newbie to C programming, don't know jack about style, convention,
etc. So I'd like comments on a little app I recently wrote.
It is called randomit.c
It is supposed to generate random integers in a certain range specified by two
endpoints inclusive. i.e.: randomit 10 100 will send to stdout a random long int
between 10 and 100. should work for negative numbers too.
My code is included. Please give me some comments!
One usefull thing you can do with it is grab a random file from a list (i.e.
directory listing): (using bash's $() instead of ``)
/bin/ls -1 | head -$(randomit 1 $(/bin/ls -1 | wc -l) ) | tail -1
My program does give an error on the printf saying it can't print long ints, or
something, why is that? (it converts my longs to ints, how do I do a format
statement for longs in printf?)
Brock
--
/---------------------------/-------------------------------------------------\
| R. Brock Lynn / http://www.geocities.com/ResearchTriangle/3328/ |
| [EMAIL PROTECTED] / Linux: The Choice of a GNU Generation! |
\---------------------/-------------------------------------------------------/
/*
TO COMPILE AND INSTALL:
gcc -O3 -m486 -pipe -o /usr/local/bin/randomit randomit.c
This thing is licensed under the infamous GPL! (or copyleft in some circles)
Modify and improve to your heart's content, however please *do* mention my name
in the credits of your modified works if you distribute them. And as always, any
work based on this must remain free, and you must provide source code for your
work, modifications and all to all comers.
One application of this is to randomly choose a file from a directory listing:
/bin/ls -1 | head -$(randomit 1 $(/bin/ls -1 | wc -l) ) | tail -1
I hope it's useful for other things too!
LONG LIVE THE SHELL SCRIPT!!!! :)
* NOTE: This program is based on "rand, srand, and time"
in the standard C library. As such it is limited in how "random" it is.
I use the system time (which gets updated every second, and not any quicker)
as the seed value to srand. The effect of this is that all random numbers
generated by this program within the same second will be the same. Sorry
about the inconvenience. Maybe a better way of seeding is to sample the mic
input of the sound card for the random data generated by background noise???
Or maybe us a very quick race condition to test which mini-process won and
use that as the seed? Oh well, as you can see, there is room for improvement!
R. Brock Lynn
May 20, 1998
*/
/*
RandomIt version 0.01, shell utility for generating pseudo-random numbers.
Copyright (C) 1998 R. Brock Lynn <[EMAIL PROTECTED]>. RandomIt comes with
ABSOLUTELY NO WARRANTY; for details type `randomit --warranty'. This is free
software, and you are welcome to redistribute it under certain conditions;
type `randomit --license' for details.
Usage: randomit <start> <end>
Example: randomit 0 100
(picks a random integer from 0 to 100 inclusive)
<start> and <end> must be integers,
or you will get strange results.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#define MAX(a,b) a > b ? a : b
#define MIN(a,b) a < b ? a : b
int main ( int argc, char *argv[] ) {
char* name ;
long start, end, randy ;
char* usage = "\nRandomIt version 0.01, shell utility for generating
pseudo-random numbers.\nCopyright (C) 1998 R. Brock Lynn <[EMAIL PROTECTED]>.
RandomIt comes with\nABSOLUTELY NO WARRANTY; for details type `%s --warranty'. This
is free\nsoftware, and you are welcome to redistribute it under certain
conditions;\ntype `%s --license' for details.\n\nUsage: %s <start> <end>\n\nExample:
%s 0 100\n(picks a random integer from 0 to 100 inclusive)\n\n<start> and <end> must
be integers,\nor you will get strange results.\n\n" ;
char* warranty =
"\n----------------------------------------------------------------------------\n\nNO
WARRANTY\n\nBECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR\nTHE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN\nOTHERWISE
STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES\nPROVIDE THE PROGRAM \"AS
IS\" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED\nOR IMPLIED, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF\nMERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE. THE ENTIRE RISK AS TO\nTHE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH
YOU. SHOULD THE PROGRAM\nPROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
SERVICING, REPAIR OR\nCORRECTION.\n\nIN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR
AGREED TO IN WRITING\nWILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY
AND/OR\nREDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR
DAMAGES,\nINCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
ARISING\nOUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO\nLOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
OR\nTHIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER\nPROGRAMS),
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE\nPOSSIBILITY OF SUCH
DAMAGES.\n\n----------------------------------------------------------------------------\n\n"
;
char* license =
"\n----------------------------------------------------------------------------\n\nGNU
GENERAL PUBLIC LICENSE\n\n(This document also available via the Internet
at\nhttp://www.gnu.org/copyleft/gpl.html)\n\nVersion 2, June 1991\n\nCopyright (C)
1989, 1991 Free Software Foundation, Inc.\n59 Temple Place - Suite 330, Boston, MA
02111-1307, USA\n\nEveryone is permitted to copy and distribute verbatim copies\nof
this license document, but changing it is not allowed.\n\nPreamble\n\nThe licenses for
most software are designed to take away your freedom to\nshare and change it. By
contrast, the GNU General Public License is intended\nto guarantee your freedom to
share and change free software--to make sure\nthe software is free for all its users.
This General Public License applies\nto most of the Free Software Foundation's
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APPLICABLE LAW. EXCEPT WHEN\nOTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR
OTHER PARTIES\nPROVIDE THE PROGRAM \"AS IS\" WITHOUT WARRANTY OF ANY KIND, EITHER
EXPRESSED\nOR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF\nMERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO\nTHE
QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM\nPROVE
DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR
OR\nCORRECTION.\n\n12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
WRITING\nWILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY
AND/OR\nREDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR
DAMAGES,\nINCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES
ARISING\nOUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO\nLOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
OR\nTHIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER\nPROGRAMS),
EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE\nPOSSIBILITY OF SUCH
DAMAGES.\n\nEND OF TERMS AND
CONDITIONS\n\n----------------------------------------------------------------------------\n\n"
;
/* Get basename of how the program was called,
if argv[0] == "/this/is/the/path/to/the/prog" then we want "prog" */
name = argv[0] + strlen ( argv[0] ) - 1 ;
while ( name > argv[0] && *(name - 1) != '/' ) -- name ;
switch ( argc ) {
case 3: {
start = (long) MIN ( atoi ( argv[1] ) , atoi ( argv[2] ) ) ;
end = (long) MAX ( atoi ( argv[1] ) , atoi ( argv[2] ) ) ;
srand ( time ( 0 ) ) ;
randy = ( (float) rand() / (float) RAND_MAX ) * ( end - start
+ 1 ) + start ;
printf ( "%d\n", randy ) ;
}
break ;
case 2: {
if ( ! strcmp ( argv[1], "--license" ) ) printf ( license ) ;
else if ( ! strcmp ( argv[1], "--warranty" ) ) printf (
warranty ) ;
else printf ( usage, name, name, name, name ) ;
}
break ;
default: printf ( usage, name, name, name, name ) ;
}
return 0 ;
}
