function to split a filepath into path and file

Question

Lets say I have a function:

void split_path_file(char** p, char** f, char *pf)
{
    //malloc and set *p to file path, malloc and set *f to file name
    //p         


        

Answer 1

The simplest way seems to be to start from the end and work towards the beginning, looking for the first delimiter character. You then have two cases: either you found one or you didn't. Something like this should do it for you:

#include 
#include 

void split_path_file(char **p, char **f, char *pf) {
  char *newcopy = malloc(strlen(pf) + 1);
  strcpy(newcopy, pf);

  for (z=newcopy+strlen(newcopy); z>newcopy; z--) {
    if (*z == '/' || *z == '\\')
      break;
  }

  if (z > newcopy) {
    *p = newcopy;
    *z = '\0';
    *f = z+1;
  } else {
    *f = newcopy;
    *p = NULL;
  }
}

Update: @ephemient's comment below points out the above approach doesn't leave *p and *f suitable for calling free(). If this is important, something a little more complicated like this will be needed:

#include 
#include 

void split_path_file(char **p, char **f, char *pf) {

  /* Find last delimiter. */
  char *z;
  for (z=pf+strlen(pf); z>=pf; z--) {
    if (*z == '/' || *z == '\\')
      break;
  }

  if (z >= pf) {
    /* There is a delimiter: construct separate
       path and filename fragments. */
    printf("--> %i\n", z-pf);
    *p = malloc(z-pf+1);
    strncpy(*p, pf, z-pf);
    (*p)[z-pf] = '\0';
    *f = malloc(strlen(z));
    strcpy(*f, z+1);
  } else {
    /* There is no delimiter: the entire
       string must be a filename. */
    *p = NULL;
    *f = malloc(strlen(pf)+1);
    strcpy(*f, pf);
  }
}