Splitting a string by a delimiter in C

Given a path

/level1/level2/level3/level4

I want to be able to split this string such that I can retrieve each individual entry,
i.e "level1", "level2", "level3", "level4".

Now my first idea was using strtok, but apparently most people recommend against using this function. What is another approach so that I can pass in a string (char* path) and get each entry split at "/".

Solution

Splitting Unix paths is more than just splitting on /. These all refer to the same path...

/foo/bar/baz/
/foo/bar/baz
/foo//bar/baz

As with many complex tasks, it's best not to do it yourself, but to use existing functions. In this case there are the POSIX dirname and basename functions.

dirname returns the parent path in a filepath
basename returns the last portion of a filepath

Using these together, you can split Unix paths.

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <libgen.h>

int main(void) {
    char filepath[] = "/foo/bar//baz/";

    char *fp = filepath;
    while( strcmp(fp, "/") != 0 && strcmp(fp, ".") != 0 ) {
        char *base = basename(fp);
        puts(base);

        fp = dirname(fp);
    }

    // Differentiate between /foo/bar and foo/bar
    if( strcmp(fp, "/") == 0 ) {
        puts(fp);
    }
}

// baz
// bar
// foo
// /

It's not the most efficient, it does multiple passes through the string, but it is correct.