Delimiting path using strtok() - c

Question

I'm trying to obtain a file from its path.
This is my code:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char split_path(char *path){
char *str1, *delim;
char buf[255];
int i, max;
char *token = "/";
for (i = 1, str1 = path; ; i++, str1 = NULL){
delim = strtok(str1, token);
if (delim == NULL){
break;
}
buf[i] = *delim;
max = i;
}
char last = buf[max];
return last;
}
int main(int argc, char *argv[]){
if (argc != 3){
fprintf(stderr, "Usage: %s string delim\n", argv[0]);
exit(EXIT_FAILURE);
}
char last = split_path(argv[1]);
printf("%c\n", last);
return 0;
}
So if I enter an input of /a/b/c/d , it returns 'd' which is what I want.
But if I enter an input of /a/b/c/d.txt, it only returns 'd' without the '.txt', when what I need is 'd.txt'.
It seems to be only getting the first index after the last / . I can't seem to figure out the problem.
Help much appreciated.

Answer 1

Your problem is split_path is returning the first letter of the last good result of strtok.
Change split_path to return a string, and modify it slightly... something like this:
char *split_path(char *path){
char *str1, *delim;
int i, max;
char *last = NULL;
char *token = "/";
for (i = 1, str1 = path; ; i++, str1 = NULL){
delim = strtok(str1, token);
if (delim == NULL){
break;
}
last = delim;
}
return last;
}
int main(int argc, char *argv[]){
if (argc != 3){
fprintf(stderr, "Usage: %s string delim\n", argv[0]);
exit(EXIT_FAILURE);
}
char *last = split_path(argv[1]);
printf("%s\n", last);
return 0;
}

Answer 2

I'll show you how to do it two ways. The easiest is to include libgen.h and use basename(), if this exists on your system. It does what you wanted. But if you want to write your own function, you can do it with strrchr(), which finds the last occurrence of a character in a string.
#include <stdio.h>
#include <string.h> // for strrchr()
#include <libgen.h> // for basename()
const char *my_basename(const char *path)
{
const char *lastSlash = strrchr(path, '/');
if (lastSlash)
return lastSlash+1;
return path;
}
int main(int argc, char *argv[])
{
if (argc < 2)
return;
printf("Full path = %s\n", argv[1]);
printf("basename() = %s\n", basename(argv[1]));
printf("my_basename() = %s\n", my_basename(argv[1]));
return 0;
}
Sample output:
Full path = /aaa/bbb/ccc/ddd.txt
Filename = ddd.txt
Filename = ddd.txt