Question

I’m trying to check if a file is a folder but when I change this line:

snprintf(buf, sizeof buf, "%s\\%s", path, e->d_name);
                             ^      ^
                             +------+ note the differences

To this:

snprintf(buf, sizeof buf, "%s\b%s", d->dd_name, e->d_name);
                             ^      ^
                             +------+ note the differences

It does not print “is folder” or “is file” because stat(...) fails. Although both lines generate same output path.

Whats going on?

---

The code:

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>

int main(int argc, char** argv) {
    DIR *d;
    struct dirent *e;
    struct stat fs;
    char*path = "C:\\Users\\Me\\Documents\\NetBeansProjects\\MyApp";
    d = opendir(path);
    if (d != NULL) {
        while (e = readdir(d)) {
            char buf[256];
            snprintf(buf, sizeof buf, "%s\\%s", path, e->d_name); // <- here
            printf("%s\n",buf);
            if (stat(buf, &fs) < 0) continue;
            if (S_ISDIR(fs.st_mode)) {
                printf("is folder");
            } else {
                printf("is file");
            }
        }
        closedir(d);
    }

    return 0;
}

Answer 1

The advice from Mat is sound; there are no documented publicly accessible members in a DIR structure, and you should not be trying to use d->dd_name, therefore.

However, if you want to remove an asterisk from the end of a string, then you cannot use backspace to do that. A backspace only erases a character when typed at a terminal. Otherwise, it is just a control character in a string. You could use:

snprintf(buf, sizeof(buf), "%.*s%s", (int)strlen(d->dd_name)-1, d->dd_name, e->d_name);

This would omit the last character from the d->dd_name string (leaving, I assume, a trailing slash or backslash). Note that the cast is necessary when sizeof(size_t) > sizeof(int) (as on 64-bit Unix systems); the value consumed by the * is an int.