Newbie question

[c_learner]

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.
ah!

char a[NUM+1] = "12345";
int b[5] = {0};

while(--i > -1)
{
b = atoi(&a);

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

i think i did it.

a='\0';
}

return 0;
}

/* 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=NUM;
char a[NUM+1] ="12345";
int b[NUM] = {0};

while(--i > -1)
{
b = atoi(&a);
a='\0';
}

return 0;
}

 

[Michael Mair]

goose wrote:

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.

ah!

char a[NUM+1] = "12345";
int b[5] = {0};

while(--i > -1)
{
b = atoi(&a);

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

i think i did it.

Nope. You took up my suggestion about getting rid of c --
which, ironically, was the least important and most
peril-ridden part...

atoi() does not give you a chance for error checking.
I.e.
- use strtol() if you want to stick with your approach
- use isdigit() from <ctype.h> to check whether you really
have a digit before either
- using atoi() (unnecessarily); or
- using b = a - '0'


Cheers
Michael

a='\0';
}

return 0;
}

/* 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=NUM;
char a[NUM+1] ="12345";
int b[NUM] = {0};

while(--i > -1)
{
b = atoi(&a);
a='\0';
}

return 0;
}

 

[c_learner]

Nope. You took up my suggestion about getting rid of c --
which, ironically, was the least important and most
peril-ridden part...

atoi() does not give you a chance for error checking.
E-Mail: Mine is an /at/ gmx /dot/ de address.

error checking, it's easy.

/* coded by c_learner, released under GPL v2
(http://www.gnu.org/copyleft/gpl.html) */
#include <stdio.h>
#include <stdlib.h>
#define NUM 5

int main(void)
{
int i=NUM;
char a[NUM+1] ="12345";
int b[NUM] = {0};

while(--i > -1)
{
if(a<'0' || a>'9')
{
perror("Invalid number!\n");
exit(1);
}
b = atoi(&a);
a='\0';
}
return 0;
}