Find the length of the string in C

//str_len returns the length of str
int str_len(char* str) {
  int len; len = 0;
   for (int i = 0; str[i] != '\\0'; i++)
   {
    len ++;
   }
   return len;
}

void main() {
  char* website = "www.github.com";
  int len = str_len(website);
  printf("length = %d n", len);
}

OUTPUT length = 17