function to split a filepath into path and file - c

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
//pf is the pointer to the full file and path "C:\sponge\bob\square.pants"
// edit: leave pf in its origional state
}
Whats the best way to accomplish this?

Answer 1

void split_path_file(char** p, char** f, char *pf) {
char *slash = pf, *next;
while ((next = strpbrk(slash + 1, "\\/"))) slash = next;
if (pf != slash) slash++;
*p = strndup(pf, slash - pf);
*f = strdup(slash);
}
(If pf == slash, then there is no directory component.)

Answer 2

Maybe a bit late to the party, but the best solution I have found and have been using for years is the two functions dirname and basename
path dirname basename
"/usr/lib" "/usr" "lib"
"/usr/" "/" "usr"
"usr" "." "usr"
"/" "/" "/"
They are great for separating parts of a path/filename. Together with realpath() they are IMHO unbeatable in simplicity and power.
http://linux.die.net/man/3/basename
http://man7.org/linux/man-pages/man3/realpath.3.html

Answer 3

Go backwards through the string until you reach the first '\\' then set *f to everything after it and *p to everything before and the '\\'.

Answer 4

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 <stdlib.h>
#include <string.h>
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 <stdlib.h>
#include <string.h>
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);
}
}

Answer 5

I came up with the following, of course this assumes that pf is malloced.
void split_path_file(char** p, char **f, char *pf)
{
char *posp = strrchr(pf, '\\');
*posp = '\0';
*p = strdup(pf);
*f = strdup(posp+1);
*posp = '\\';
}
Not sure if this is a better approach than above answers.

Answer 6

int
stripfilenameandpath (char *path, char *onlypath, char *onlyfilename)
{
/*
documentacao
path = path com path e arquivo
onlypath = somente o path
onlyfilename = somente o arquivo sem o path
*/
int ret;
int i;
int p;
char temp[255];
char *fixo;
#ifdef WIN32
const int separator = '\\';
#else
const int separator = '/';
#endif
fixo = path;
if (path == NULL)
{
if (onlypath != NULL)
{
memset (onlypath, 0, 1);
}
if (onlyfilename != NULL)
{
memset (onlyfilename, 0, 1);
}
return 1;
}
ret = strlen (path);
if (!ret)
{
if (onlypath != NULL)
{
memset (onlypath, 0, 1);
}
if (onlyfilename != NULL)
{
memset (onlyfilename, 0, 1);
}
return 0;
}
for (i = 0; i -1; i--)
{
if (temp[i] == separator)
{
temp[i + 1] = 0;
break;
}
p++;
}
p = ret - p;
fixo += p + 1;
if (onlypath != NULL)
{
strcpy (onlypath, temp);
}
if (onlyfilename != NULL)
{
strcpy (onlyfilename, fixo);
}
return 0;
}