Re: Newbie question

c_learner wrote: 
Michael Mair wrote:

c_learner wrote:

/* coded by c_learner, released under GPL v2 */ 

<OT>If you want to release something under a certain
license, provide either the license text or at least
the URI of a copy of the license</OT>

#include <stdio.h>
#include <stdlib.h>

int main() 

 int main (void)
is more expressive

{
 char i=0;


Note: Most people expect int or size_t integer loop variables.
If you have a good reason to use char, do so, of course.


 char a[6] ="12345";
 char c[2]= {0};
 char *p = a;
 int b[5] = {0};


AFAICS, p is used nowhere.
The 6 is not necessary. In fact, it may be a better
idea to use a symbolic constant, e.g. NUMDIGITS to express
the size of a (char[NUMDIGITS+1]) and b (int[NUMDIGITS])
as well as the range of the loop.


while(i < 5) 

The loop variable i is initialised at the very start of main().
If someone (maybe even you) has later on the bright idea to use
i for another loop before this one, you may be in for a surprise.
So, either set i=0; before while (i < 5) or go for a for loop
which IMO here would express in a clearer way what you are doing
with the loop.


   {
     c[0] = a[i];
     c[1] = '\0';
     b[i] = atoi(c);


You are not performing any error checking here. Either have
a look at c[0] with isdigit((unsigned char)c[0]) or use
strtol() instead of atoi() to know if something went amiss.


     printf("%d ",b[i]);
     i++;
   };
 putchar('\n');

 return 0;
}


Note: You do not need c if you
- go for the canonical a[i] - '0'; or
- run the other way through a and set a[i+1] to zero before
  passing &a[i] to atoi()/strtol() (this effectively destroys
  the information in a);

Another approach could make use of a reference string literal
char digits[] = "0123456789"; and p = strchr(digits, a[i]);
where, for non-NULL p, b[i] becomes p - digits.


Cheers
 Michael
--
E-Mail: Mine is an   /at/ gmx /dot/ de   address.




Firstly, top-posting on clc earns you a spanking!
*spank*
*spank*
*spank*

There

Now see that it doesn't happen again :-)

> /* Thanks */
> /* coded by c_learner, released under GPL v2
> (http://www.gnu.org/copyleft/gpl.html) */
> #include <stdlib.h>
> #define NUM 5
>
> int main(void)
> {
>   int i = 5;

Since you have #define NUM, why not use NUM here? When the
array size changes to 7, you will then only have to change
the #define, and not hunt down all the places where you used
the magic number 5.

>   char a[NUM+1] = "12345";
>   int b[5] = {0};
>
>   while(--i > -1)
>     {
>       b[i] = atoi(&a[i]);

Once again, you've used the dreaded atoi(). Why not
change this as suggested above by MM?

>       a[i]='\0';
>     }
>
>   return 0;
> }
>
>
.

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