pointers and strlen

Hello
I have this code

Code:

---

int mystrlen(char *string) {
       
        int len;
        char *p = string;

        for(; string[0] != '\0'; string++)
                      ;
len = p - &string[0];
return len;
}

---

It works but i dont how. I mean string[0] != '\0' will be always true if the string is > 0 and it is. How can len be the lenght if p points to the begining of string? I suppose p points wherever string does, right?
I was wondering how can i write this function without pointer p..

Thanks

>I was wondering how can i write this function without pointer p.

Code:

---

int mystrlen(const char *s)
{
  int len = 0;
  while ( *s++ != '\0' )
  {
      ++len;
  }
  return len;
}

---

Or do this:

Code:

---

int mystrlen(const char *s)
{
  int len = 0;
  while ( s[len++] != '\0' );

  return len-1; /*edit*/
}

---

Or just do that:

Code:

---

int mystrlen( const char *s )
{
    return *s == '\0' ? 0 : 1 + mystrlen( s+1 );
}

---

Or do...

Quzah.

quzah, your first version doesn't work properly ;)

Another "or do":

Code:

---

int mystrlen(const char *s)
{
  const char *p = s;
  while (*p) p++;
  return p - s;
}

---

Quote:

---

Originally posted by Hammer
quzah, your first version doesn't work properly ;)

Another "or do":

---

Yeah but at least it fit the criteria. ;)

Oh, and technicly, to fit criteria, you could rename your pointer 'q' instead of 'p' and do it "without pointer p". :D

Quzah.

>>but at least it fits the criteria
Doh, I didn't even bother reading that :rolleyes:

Here's another way:

Code:

---

int mystrlen( const char *s )
{
    return strlen(s);
}

---

:D

#define mystrlen strlen

But now I'm just being ridicules.

Quzah.

Quote:

---

Originally posted by quzah
Here's another way:

Code:

---

int mystrlen( const char *s )
{
    return strlen(s);
}

---

---

I knew someone would show this one -- I was afraid it was going to be me! Thanks for beating me to it, Q

>len = p - &string[0];

I was getting negative numbers using the above.
len = &string[0] - p;

Hammer, your code should be:

Code:

---

int mystrlen(char *s)
{
  const char *p = s;
  while(*s++ && *s);
  return s - p;
}

---

Quote:

---

Originally posted by cc0d3r
Hammer, your code should be:

Code:

---

int mystrlen(char *s)
{
  const char *p = s;
  while(*s++ && *s);
  return s - p;
}

---

---

both his and your code works , but his while loop is different

>>Hammer, your code should be:<<
Why exactly? What is the purpose of the two tests in your code?

Never mind