Recursively list directories in C

Question

im looking for a code who will recursively list all directories and files of a directory given on argument in C programming, ive find an interresting code (below) but I dont understand the snprintf function and particulary the "/", I would prefer to use strcat or other system function to override the sprintf function but I dont see how since I dont understand what the snprintf do here. Heres the code:

int is_directory_we_want_to_list(const char *parent, char *name) {
    struct stat st_buf;
    if (!strcmp(".", name) || !strcmp("..", name))
        return 0;

    char *path = alloca(strlen(name) + strlen(parent) + 2);
    sprintf(path, "%s/%s", parent, name);
    stat(path, &st_buf);
    return S_ISDIR(st_buf.st_mode);
}

int list(const char *name) {
    DIR *dir = opendir(name);
    struct dirent *ent;

    while (ent = readdir(dir)) {
        char *entry_name = ent->d_name;
        printf("%s\n", entry_name);

        if (is_directory_we_want_to_list(name, entry_name)) {
            // You can consider using alloca instead.
            char *next = malloc(strlen(name) + strlen(entry_name) + 2);
            sprintf(next, "%s/%s", name, entry_name);
            list(next);
            free(next);
        }
    }

    closedir(dir);
}

from How to recursively list directories in C on LINUX

Okay, my program is running but now i want to save all the file and directory printed to a file like i run my program ./a.out . > buffer where buffer contain what the program should print on the shell

uh... what snprintf call? There's none in the code snippet. If you don't understand what it does, why don't you LOOK UP what it does? http://www.cplusplus.com/reference/cstdio/snprintf/ — Marc B, Jul 03 '13 at 16:59
what is your problem with sprintf exactly? it's just concatenating 3 strings - name, "/" and entry_name. — Tom Tanner, Jul 03 '13 at 17:00

score 1 · Accepted Answer · answered Jul 03 '13 at 16:59

1

the line

sprintf(next, "%s/%s", name, entry_name);

could be replaced with

strcpy (next, name);
strcat (next, "/");
strcat (next, entry_name);

and it would do the same thing. Does that clarify it for you?

answered Jul 03 '13 at 16:59

Jules

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that was fast, yes i get it a lot better now thank you, and yes it was sprintf, sorry – Saxtheowl Jul 03 '13 at 17:02
1

Do note that every call to `strcat()` involves walking the entire string to find the end of it, so a single `sprintf()` call here is much more efficient. – Adam Rosenfield Jul 03 '13 at 17:05

Recursively list directories in C

1 Answers1