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| From | bartekltg <bartekltg@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Program to compute amount of coins |
| Date | 2015-09-03 23:37 +0200 |
| Organization | ATMAN - ATM S.A. |
| Message-ID | <msaej7$msp$1@node2.news.atman.pl> (permalink) |
| References | (3 earlier) <Ns%Fx.510855$JH3.131464@fx37.am4> <msa1e1$9oq$1@node2.news.atman.pl> <878u8ngti7.fsf@bsb.me.uk> <msaajf$iof$1@node2.news.atman.pl> <87wpw7fcpv.fsf@bsb.me.uk> |
On 03.09.2015 22:51, Ben Bacarisse wrote:
> bartekltg <bartekltg@gmail.com> writes:
>
>> On 03.09.2015 22:03, Ben Bacarisse wrote:
>>> bartekltg <bartekltg@gmail.com> writes:
>>> <snip>
>>>> I'm sure that these loops teacher mentioned was a loop over "face
>>>> value".
>>>
>>> Yes, that must surely be it.
>>>
>>>> #include <stdio.h>
>>>> #include <math.h>
>>>>
>>>> int main(void)
>>>> {
>>>> double amount;
>>>> const unsigned int coin_value[]= {25,10, 5,1 } ;
>>>>
>>>> printf ("Please, enter your amount in $: \n");
>>>>
>>>> if (scanf("%lf", &amount) == 1)
>>>> {
>>>> if (amount > pow(2.0,32.0)*0.9999){
>>>
>>> That's an odd number to test against. For 32-bit unsigned ints things
>>> go wrong for values < 0 and >= pow(2, 32)/100.
>>
>> Yes.
>> I was thinking about 0.00999. Probably:)
>
> Ah, right. Mind you, that's still odder than just dividing by the
> multiplier you are going to use later (100), and the difference (2**32 x
> 0.00001) still over 42,949. Not that that really matters here since
I just tried too hard to be safe ;-)
> it's an exercise, but there is serious point to be made: it's good to
> avoid things that make the reader think more than they need to. I'd
> have to ask myself why 0.00999? Is is safe? It is too conservative?
> Does that matter? And so on.
It looks like you think about this much more than I did.
I should comment this line.
// 2^32/100 * 0.99999 is the maximal number of quater
coins that can be given as change in retail stores.
> <snip>
>> Or hardcode array length.
>> But your version is safer.
>> const int N = 5;
>> int coin_value[N]= {25, 10, 5,1};
>> do not generates a error or warning,
>> and the last entry is uninitialized.
>
> And that's a "variable length array" in C (it isn't in C++) and these
> (much to my dismay) has been made optional in C11.
Are you sure this is the problem?
I compiled it in c++ with
-Wall -Wpedantic -Wextra -std=c++98
(so no variable length arrays) and it still work and do not generate
any warnings.
N is const.
bartekltg
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Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 08:54 -0700
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 17:07 +0100
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 10:02 -0700
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 10:12 -0700
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 10:18 -0700
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 18:30 +0100
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-03 19:53 +0200
Re: Program to compute amount of coins Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-03 21:03 +0100
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-03 22:29 +0200
Re: Program to compute amount of coins Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-03 21:51 +0100
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-03 23:37 +0200
Re: Program to compute amount of coins Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-03 23:07 +0100
Re: Program to compute amount of coins James Kuyper <jameskuyper@verizon.net> - 2015-09-03 18:24 -0400
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-04 00:30 +0200
Re: Program to compute amount of coins Keith Thompson <kst-u@mib.org> - 2015-09-03 16:36 -0700
Re: Program to compute amount of coins Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-06 14:00 -0700
Re: Program to compute amount of coins Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-06 13:58 -0700
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-07 05:07 +0200
Re: Program to compute amount of coins Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-07 13:14 +0100
Re: Program to compute amount of coins Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-08 02:39 -0700
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-08 18:29 +0200
Re: Program to compute amount of coins James Kuyper <jameskuyper@verizon.net> - 2015-09-08 13:15 -0400
Re: Program to compute amount of coins Keith Thompson <kst-u@mib.org> - 2015-09-08 10:16 -0700
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-04 04:09 -0700
Re: Program to compute amount of coins Bartc <bc@freeuk.com> - 2015-09-04 12:16 +0100
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-04 14:11 +0200
Re: Program to compute amount of coins Ike Naar <ike@iceland.freeshell.org> - 2015-09-04 19:06 +0000
Re: Program to compute amount of coins James Kuyper <jameskuyper@verizon.net> - 2015-09-04 15:12 -0400
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-05 01:54 +0200
Re: Program to compute amount of coins Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-09-05 01:01 +0100
Re: Program to compute amount of coins bartekltg <bartek@gmail.com> - 2015-09-05 02:50 +0200
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-03 18:09 +0200
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 17:11 +0100
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-03 18:38 +0200
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 10:08 -0700
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 18:20 +0100
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-03 19:32 +0200
Re: Program to compute amount of coins Keith Thompson <kst-u@mib.org> - 2015-09-03 12:18 -0700
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 10:16 -0700
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 18:24 +0100
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 10:37 -0700
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 19:02 +0100
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-03 10:42 -0700
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-03 19:57 +0200
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 19:05 +0100
Re: Program to compute amount of coins Bartc <bc@freeuk.com> - 2015-09-03 21:23 +0100
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-03 21:55 +0100
Re: Program to compute amount of coins Keith Thompson <kst-u@mib.org> - 2015-09-03 16:39 -0700
Re: Program to compute amount of coins Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-06 14:02 -0700
Re: Program to compute amount of coins Keith Thompson <kst-u@mib.org> - 2015-09-06 17:04 -0700
Re: Program to compute amount of coins Alla _ <modelling.data@gmail.com> - 2015-09-04 03:48 -0700
Re: Program to compute amount of coins bartekltg <bartekltg@gmail.com> - 2015-09-04 14:04 +0200
Re: Program to compute amount of coins Richard Heathfield <rjh@cpax.org.uk> - 2015-09-04 14:23 +0100
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