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Groups > comp.lang.c > #67931 > unrolled thread
| Started by | Alla _ <modelling.data@gmail.com> |
|---|---|
| First post | 2015-08-21 04:39 -0700 |
| Last post | 2015-08-30 02:14 -0700 |
| Articles | 7 on this page of 47 — 12 participants |
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Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-21 04:39 -0700
Re: Initializing sum to zero wouldn't compile James Kuyper <jameskuyper@verizon.net> - 2015-08-21 07:54 -0400
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-21 05:27 -0700
Re: Initializing sum to zero wouldn't compile Keith Thompson <kst-u@mib.org> - 2015-08-21 10:28 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-21 11:15 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-21 05:30 -0700
Re: Initializing sum to zero wouldn't compile Ike Naar <ike@iceland.freeshell.org> - 2015-08-21 12:40 +0000
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-21 11:16 -0700
Re: Initializing sum to zero wouldn't compile Siri Cruz <chine.bleu@yahoo.com> - 2015-08-21 07:41 -0700
Re: Initializing sum to zero wouldn't compile Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-08-21 10:56 -0400
Re: Initializing sum to zero wouldn't compile Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2015-08-21 09:28 -0600
Re: Initializing sum to zero wouldn't compile Barry Schwarz <schwarzb@dqel.com> - 2015-08-21 10:02 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-21 11:21 -0700
Re: Initializing sum to zero wouldn't compile Barry Schwarz <schwarzb@dqel.com> - 2015-08-21 22:27 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-22 02:25 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-22 03:50 -0700
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-22 13:18 +0100
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-22 11:21 -0700
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-22 21:55 +0100
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-26 01:36 -0700
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-26 11:24 +0100
Re: Initializing sum to zero wouldn't compile Barry Schwarz <schwarzb@dqel.com> - 2015-08-22 17:17 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-26 01:26 -0700
Re: Initializing sum to zero wouldn't compile Barry Schwarz <schwarzb@dqel.com> - 2015-08-26 02:27 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-26 04:21 -0700
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-26 12:37 +0100
Re: Initializing sum to zero wouldn't compile Richard Heathfield <rjh@cpax.org.uk> - 2015-08-26 13:06 +0100
Re: Initializing sum to zero wouldn't compile Bartc <bc@freeuk.com> - 2015-08-26 13:43 +0100
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-26 14:03 +0100
Re: Initializing sum to zero wouldn't compile Richard Heathfield <rjh@cpax.org.uk> - 2015-08-26 14:06 +0100
Re: Initializing sum to zero wouldn't compile Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-06 15:14 -0700
Re: Initializing sum to zero wouldn't compile Keith Thompson <kst-u@mib.org> - 2015-08-26 11:38 -0700
Re: Initializing sum to zero wouldn't compile Keith Thompson <kst-u@mib.org> - 2015-08-26 11:44 -0700
Re: Initializing sum to zero wouldn't compile Barry Schwarz <schwarzb@dqel.com> - 2015-08-22 10:49 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-22 11:16 -0700
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-29 07:19 -0700
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-29 15:35 +0100
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-30 02:11 -0700
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-30 12:28 +0100
Re: Initializing sum to zero wouldn't compile Keith Thompson <kst-u@mib.org> - 2015-08-30 15:02 -0700
Re: Initializing sum to zero wouldn't compile Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-08-30 22:36 +0100
Re: Initializing sum to zero wouldn't compile Keith Thompson <kst-u@mib.org> - 2015-08-30 16:10 -0700
Re: Initializing sum to zero wouldn't compile Bartc <bc@freeuk.com> - 2015-08-31 00:14 +0100
Re: Initializing sum to zero wouldn't compile Keith Thompson <kst-u@mib.org> - 2015-08-30 19:56 -0700
Re: Initializing sum to zero wouldn't compile Bartc <bc@freeuk.com> - 2015-08-29 16:57 +0100
Re: Initializing sum to zero wouldn't compile Bartc <bc@freeuk.com> - 2015-08-29 17:37 +0100
Re: Initializing sum to zero wouldn't compile Alla _ <modelling.data@gmail.com> - 2015-08-30 02:14 -0700
Page 3 of 3 — ← Prev page 1 2 [3]
| From | Ben Bacarisse <ben.usenet@bsb.me.uk> |
|---|---|
| Date | 2015-08-30 22:36 +0100 |
| Message-ID | <877focwja7.fsf@bsb.me.uk> |
| In reply to | #68725 |
Keith Thompson <kst-u@mib.org> writes: > Ben Bacarisse <ben.usenet@bsb.me.uk> writes: >> Alla _ <modelling.data@gmail.com> writes: > [...] >>> As to arrays, I am using an array because this >>> exercise is part of the chapter on arrays. >> >> Ah. Then I suspect you are doing it wrong. Using an array in a >> pointless way is unlikely to be what the exercise wants. > > I disagree. I think the exercise (to compute the average of three > floating-point values using an array) has two parts: to read values > into an array, and to compute the average of the values in an array. > Both are sensible things to do. The fact that the combination > is more easily done without using an array would be relevant in a > real-world program, but not in an introductory exercise. It looks like we agree but you say that you disagree so I must have made my point badly. Assigning to an array element which is then ignored is "doing it wrong" and "unlikely to be what the exercise wants". What you describe is what the exercise probably wants. -- Ben.
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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Date | 2015-08-30 16:10 -0700 |
| Message-ID | <lnlhcstltc.fsf@kst-u.example.com> |
| In reply to | #68726 |
Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
> Keith Thompson <kst-u@mib.org> writes:
>> Ben Bacarisse <ben.usenet@bsb.me.uk> writes:
>>> Alla _ <modelling.data@gmail.com> writes:
>> [...]
>>>> As to arrays, I am using an array because this
>>>> exercise is part of the chapter on arrays.
>>>
>>> Ah. Then I suspect you are doing it wrong. Using an array in a
>>> pointless way is unlikely to be what the exercise wants.
>>
>> I disagree. I think the exercise (to compute the average of three
>> floating-point values using an array) has two parts: to read values
>> into an array, and to compute the average of the values in an array.
>> Both are sensible things to do. The fact that the combination
>> is more easily done without using an array would be relevant in a
>> real-world program, but not in an introductory exercise.
>
> It looks like we agree but you say that you disagree so I must have made
> my point badly. Assigning to an array element which is then ignored is
> "doing it wrong" and "unlikely to be what the exercise wants". What you
> describe is what the exercise probably wants.
You're right, we agree.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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| From | Bartc <bc@freeuk.com> |
|---|---|
| Date | 2015-08-31 00:14 +0100 |
| Message-ID | <ms02la$93t$1@dont-email.me> |
| In reply to | #68728 |
On 31/08/2015 00:10, Keith Thompson wrote: > Ben Bacarisse <ben.usenet@bsb.me.uk> writes: >> Keith Thompson <kst-u@mib.org> writes: >>> Ben Bacarisse <ben.usenet@bsb.me.uk> writes: >>>> Alla _ <modelling.data@gmail.com> writes: >>> [...] >>>>> As to arrays, I am using an array because this >>>>> exercise is part of the chapter on arrays. >>>> >>>> Ah. Then I suspect you are doing it wrong. Using an array in a >>>> pointless way is unlikely to be what the exercise wants. >>> >>> I disagree. I think the exercise (to compute the average of three >>> floating-point values using an array) has two parts: to read values >>> into an array, and to compute the average of the values in an array. >>> Both are sensible things to do. The fact that the combination >>> is more easily done without using an array would be relevant in a >>> real-world program, but not in an introductory exercise. >> >> It looks like we agree but you say that you disagree so I must have made >> my point badly. Assigning to an array element which is then ignored is >> "doing it wrong" and "unlikely to be what the exercise wants". What you >> describe is what the exercise probably wants. > > You're right, we agree. (It's odd but on my Thunderbird newsreader, your posts seem to be an hour ahead of everyone else's. So I will first read someone's reply to your post, /then/ read your original post as it has a later time-stamp! This happens when using un-threaded view and sorting chronologically. But the time-stamps are still out of order in threaded view.) -- Bartc
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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Date | 2015-08-30 19:56 -0700 |
| Message-ID | <lnh9ngtbbr.fsf@kst-u.example.com> |
| In reply to | #68731 |
Bartc <bc@freeuk.com> writes:
[...]
> (It's odd but on my Thunderbird newsreader, your posts seem to be an
> hour ahead of everyone else's. So I will first read someone's reply to
> your post, /then/ read your original post as it has a later time-stamp!
>
> This happens when using un-threaded view and sorting chronologically.
> But the time-stamps are still out of order in threaded view.)
The clock on the system I'm posting from is about 35 minutes fast.
I'll talk to the owner.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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| From | Bartc <bc@freeuk.com> |
|---|---|
| Date | 2015-08-29 16:57 +0100 |
| Message-ID | <mrskm0$8n3$1@dont-email.me> |
| In reply to | #68630 |
On 29/08/2015 15:19, Alla _ wrote:
> Thank you Everyone! I have again learned a lot from you.
> Still working on this 'simple' program. Here is an improved
> version, which still has an important bug:
>
> // a program that calculates the average of an array of 3 floating-point values; with for loop
>
> #include <stdio.h>
>
> int main (void)
> {
> float values[3];
> float element;
> float sum = 0;
> int i;
>
> printf ("Please, enter 3 floating values: \n");
>
> for ( i = 0; i < 3; i++)
> {
> if (scanf ("%f", &element) == 1)
> {
> if (element <= 0)
> printf ("Please, enter positive values\n");
> i--; /* if I don't decrement i, then the program
> will go on 'counting' wrong values and
> produce erroneous result; but both i--; and
> i -= i do not work; I get an error message (see
> below)
I revised your code so that it compiles (and also so it was more
consistent):
#include <stdio.h>
int main (void)
{
float values[3];
float element;
float sum = 0;
int i;
printf ("Please, enter 3 floating values: \n");
for ( i = 0; i < 3; i++) {
if (scanf ("%f", &element) == 1) {
if (element <= 0) {
printf ("Please, enter positive values\n");
i--;
} else {
printf("Read %f\n",element);
values[i] = element;
sum += values[i];
}
} else {
printf ("You entered special characters\n");
return;
}
}
printf ("The average of 3 values is %.2f\n", sum / 3);
return 0;
}
When a negative value has been entered, it's not clear what you
intentions are; are uses supposed to re-enter the number?
That won't work if all the input is on one line, as in:
10 -20 30
As all numbers will already be read in; it will proceed to read 30 then
one more number. (The extra printf will show what is being processed.)
It's easier to if numbers are entered one per line; you will have to
specify this.
You might also consider first reading all the numbers into the array,
then working out the average of the numbers in the array.
--
Bartc
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| From | Bartc <bc@freeuk.com> |
|---|---|
| Date | 2015-08-29 17:37 +0100 |
| Message-ID | <mrsn1p$huc$1@dont-email.me> |
| In reply to | #68638 |
On 29/08/2015 17:07, Stefan Ram wrote:
> Bartc <bc@freeuk.com> writes:
>> printf ("You entered special characters\n");
>> return;
>
> »'return' with no value, in function returning non-void«
gcc doesn't trap that in default warning mode.
> Please, enter 3 floating values:
> 9999999933815812510711506376257961984.000000
> Read 9999999933815812510711506376257961984.000000
> 9999999933815812510711506376257961984.000000
> Read 9999999933815812510711506376257961984.000000
> 9999999933815812510711506376257961984.000000
> Read 9999999933815812510711506376257961984.000000
> The average of 3 values is 10000000567641112624826207124609564672.00
The program uses float calculations; try double (with scan %lf), or
printing values using "%.6e".
--
Bartc
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| From | Alla _ <modelling.data@gmail.com> |
|---|---|
| Date | 2015-08-30 02:14 -0700 |
| Message-ID | <35c27f8e-afe0-4016-aef8-3d0411db815a@googlegroups.com> |
| In reply to | #68638 |
On Saturday, August 29, 2015 at 7:57:44 PM UTC+4, Bart wrote:
> On 29/08/2015 15:19, Alla _ wrote:
> > Thank you Everyone! I have again learned a lot from you.
> > Still working on this 'simple' program. Here is an improved
> > version, which still has an important bug:
> >
> > // a program that calculates the average of an array of 3 floating-point values; with for loop
> >
> > #include <stdio.h>
> >
> > int main (void)
> > {
> > float values[3];
> > float element;
> > float sum = 0;
> > int i;
> >
> > printf ("Please, enter 3 floating values: \n");
> >
> > for ( i = 0; i < 3; i++)
> > {
> > if (scanf ("%f", &element) == 1)
> > {
> > if (element <= 0)
> > printf ("Please, enter positive values\n");
> > i--; /* if I don't decrement i, then the program
> > will go on 'counting' wrong values and
> > produce erroneous result; but both i--; and
> > i -= i do not work; I get an error message (see
> > below)
>
> I revised your code so that it compiles (and also so it was more
> consistent):
>
>
> #include <stdio.h>
>
> int main (void)
> {
> float values[3];
> float element;
> float sum = 0;
> int i;
>
> printf ("Please, enter 3 floating values: \n");
>
> for ( i = 0; i < 3; i++) {
> if (scanf ("%f", &element) == 1) {
> if (element <= 0) {
> printf ("Please, enter positive values\n");
> i--;
> } else {
> printf("Read %f\n",element);
> values[i] = element;
> sum += values[i];
> }
> } else {
> printf ("You entered special characters\n");
> return;
> }
> }
> printf ("The average of 3 values is %.2f\n", sum / 3);
>
> return 0;
> }
>
>
> When a negative value has been entered, it's not clear what you
> intentions are; are uses supposed to re-enter the number?
>
> That won't work if all the input is on one line, as in:
>
> 10 -20 30
>
> As all numbers will already be read in; it will proceed to read 30 then
> one more number. (The extra printf will show what is being processed.)
> It's easier to if numbers are entered one per line; you will have to
> specify this.
>
> You might also consider first reading all the numbers into the array,
> then working out the average of the numbers in the array.
>
> --
> Bartc
Thank you very much!
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