slen function with recursion

[kalar]

I want to make a function slen (recursive) with arguments a pointer to string and returns the length of the string.I make this but i have segmetation fault.

#include <stdio.h>

int slen(char *p);

int main(void)
{
 char *s="hello";
 int num;

 num=slen(s);

 printf("%d\n", num);

 return 0;
}

int slen(char *p)
{
 if (*p=='\0')
   return 0;
 else
   return(slen(p++) +1);
}

any idea?

[JosAH]

any idea?

Yep, make that ++p instead of p++.

kind regards,

Jos

[kalar]

thank you very much .I was looking about half an hour and i couldn't find where the mistake was

[JosAH]

thank you very much .I was looking about half an hour and i couldn't find where the mistake was

You're welcome of course and as long as you understand the difference between
p++ and ++p and the effect it has on your recursive strlen implementation
everything's fine with me.

kind regaards,

Jos

[kalar]

I think that with p++ i am calling the function slen always with the same value.Am i right?
something else, can you tell me if i must include cases for example if the pointer is NULL(the code don't work with NULL pointer) or any other case?

[JosAH]

I think that with p++ i am calling the function slen always with the same value.Am i right?

Yep, you're right.

something else, can you tell me if i must include cases for example if the pointer is NULL(the code don't work with NULL pointer) or any other case?

That's an entirely different topic; if you're in the 'defensive programming camp'
your function might complain big time and even terminate the entire process;
a more forgiving attitude might just go astray and dump core. It's up to you.
I'd go for the 'you get what you deserve' attitude.

kind regards,

Jos