16 May
2005
16 May
'05
2:18 p.m.
print_ary (ary, DIM (ary));
void print_ary (int *aryp, int n)
{
goto skip_comma;
for (;n;aryp++, n--)
{
printf (", ");
skip_comma:
printf ("%u", *aryp);
}
printf ("\n");
}
> I'd skip both the GOTO and the conditional
and do it:
>
> void print_ary(int *aryp,size_t n)
> {
> size_t i;
> char *sep;
>
> assert(aryp != NULL); /* sorry, gotta check */
> assert(n > 0);
>
> for (i = 0 , sep = "" ; i < n ; aryp++ , i++)
> {
> printf("%s%u",sep,&aryp);
> sep = ",";
> }
> putchar('\n');
> }
Clever. I don't like the conditional either, but
you are also
unnecessarily reinitializing sep every time through the loop. With the
goto I avoid both the conditional and the reinit.
Given that the original example assumes n > 0 (the test is skipped on
first entry to the loop), you can accomplish this function with neither
an extra conditional, superfluous assignment, extra variables or use
of 'goto'
void print_arg(int *aryp, unsigned n)
{
int i;
for(i=0; ;) {
printf("%u", aryp[i]);
if(++i >= n)
break;
fputs(", ", stdout); }
putc('\n', stdout);
}
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.parse.com/~ddunfield/museum/index.html
16 May
16 May
2:33 p.m.
On 5/16/05, Dave Dunfield <dave04a at dunfield.com> wrote:
Given that the original example assumes n > 0 (the
test is skipped on
first entry to the loop), you can accomplish this function with neither
an extra conditional, superfluous assignment, extra variables or use
of 'goto'
void print_arg(int *aryp, unsigned n)
{
int i;
for(i=0; ;) {
printf("%u", aryp[i]);
if(++i >= n)
break;
fputs(", ", stdout); }
putc('\n', stdout);
}
Now that's a right answer.
-- John.
3:04 p.m.
On Mon, 2005-05-16 at 14:33 -0700, John Hogerhuis wrote:
On 5/16/05, Dave Dunfield <dave04a at
dunfield.com> wrote:
... the wrong answer being to dump out each array element followed by a
comma, then output ^H as the final step in the function ;-)
Real Programmers would presumably use putc exclusively in favour of the
more computationally expensive printf...
cheers
J.
Given that the original example assumes n > 0
(the test is skipped on
first entry to the loop), you can accomplish this function with neither
an extra conditional, superfluous assignment, extra variables or use
of 'goto'
void print_arg(int *aryp, unsigned n)
{
int i;
for(i=0; ;) {
printf("%u", aryp[i]);
if(++i >= n)
break;
fputs(", ", stdout); }
putc('\n', stdout);
}
Now that's a right answer. 
2:49 p.m.
It was thus said that the Great Dave Dunfield once stated:
Given that the original example assumes n > 0 (the test is skipped on
first entry to the loop), you can accomplish this function with neither
an extra conditional, superfluous assignment, extra variables or use
of 'goto'
void print_arg(int *aryp, unsigned n)
{
int i;
for(i=0; ;) {
printf("%u", aryp[i]);
if(++i >= n)
break;
fputs(", ", stdout); }
putc('\n', stdout);
}
Hmmm ...
void print_arg(int *aryp,size_t n)
{
printf("%u",*aryp++);
while(--n)
{
printf(",%u",*aryp++);
}
putchar('\n');
}
-spc (avoids additional variables, no GOTOs, and one conditional ... )
3:03 p.m.
On 5/16/05, Sean 'Captain Napalm' Conner <spc at conman.org> wrote:
Hmmm ...
void print_arg(int *aryp,size_t n)
{
printf("%u",*aryp++);
while(--n)
{
printf(",%u",*aryp++);
}
putchar('\n');
}
-spc (avoids additional variables, no GOTOs, and one conditional ... )
<<THUMP>> (spc just hit in the forehead by an eraser).
Straighten up and get serious. You used twice as much printf as
everybody else. Have you ever seen the setup for a printf call in
assembler?
I wonder if even the compiler can save you from this shameless bit of excess.
:-)
-- John.
3:06 p.m.
Doh! I take that back, you used half as much printf in the loop as I did.
So yours is better!
-- John.
4:06 p.m.
On Mon, 16 May 2005, John Hogerhuis wrote:
On 5/16/05, Sean 'Captain Napalm' Conner
<spc at conman.org> wrote:
I trump thee collectively:
void print_arg(int *aryp, size_t n)
{
char *t="%u,";
int i=0;
for (;(i==n-1 ? t="%u" : i<n);) printf(t, *aryp + i++);
putchar('\n');
}
A little ugly (the compiler complains about the type mismatch in the unary
expression) but otherwise it works without caveats (that I know of ;)
I suspect someone might bum it down further...no more precious time to
expend on this useless pursuit ;)
--
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
[ Old computing resources for business || Buy/Sell/Trade Vintage Computers ]
[ and academia at www.VintageTech.com || at http://marketplace.vintage.org ]
Hmmm ...
void print_arg(int *aryp,size_t n)
{
printf("%u",*aryp++);
while(--n)
{
printf(",%u",*aryp++);
}
putchar('\n');
}
-spc (avoids additional variables, no GOTOs, and one conditional ... )
<<THUMP>> (spc just hit in the forehead by an eraser).
Straighten up and get serious. You used twice as much printf as
everybody else. Have you ever seen the setup for a printf call in
assembler?
I wonder if even the compiler can save you from this shameless bit of excess. 
17 May
17 May
8:48 a.m.
Dave Dunfield wrote:
void print_arg(int *aryp, unsigned n)
{
int i;
for(i=0; ;) {
printf("%u", aryp[i]);
if(++i >= n)
break;
fputs(", ", stdout); }
putc('\n', stdout);
}
What's wrong with this (assumes that aryp[0] exists,
which the above program also assumes), shorter,
more obvious as to what is happening, etc.:
void print_arg(int *aryp, unsigned n)
{
printf("%u", aryp[0]);
for(int i=1; i<n; i++)
printf(", %u", aryp[i]);
putc('\n', stdout);
}
or are we artifically limited to using a single printf?
You can fix the aryp[0] not existing by wrapping everything
except the 'putc' in a single if (executed once per call,
not once per element)
void print_arg(int *aryp, unsigned n)
{
if (n >= 0)
{
printf("%u", aryp[0]);
for(int i=1; i<n; i++)
printf(", %u", aryp[i]);
}
putc('\n', stdout);
}
7160
days inactive
7161
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7 comments
6 participants
participants (6)
-
dave04a＠dunfield.com -
jhoger＠gmail.com -
julesrichardsonuk＠yahoo.co.uk -
kth＠srv.net -
spc＠conman.org -
vcf＠siconic.com