Directory Related Calls in C Language

Here are the summary of the system calls to manipulate the directories.

Function	Description	Returns
mkdir(const char * pathname, mode)	Create a dirctory	0 if OK, -1 on error
rmdir(const char * pathname)	Delete a directory	0 if OK, -1 on error
opendir(const char * pathname)	Open a directory	Pointer of DIR if OK, NULL on error
readdir(DIR * dp)	Read a directory	Pointer of dirent if OK, NULL at the end of directory or error
closedir(DIR * dp)	Close a directory	0 if OK, -1 on error

In *nix, we have a special data structure for a directory, namelyDIRanddirent.

DIRis a structure for directory streams, anddirenthas the following members:

• ino_t d_ino

  : file serial number

• char d_name[]

  : Name of entry.

Example

In the following, we try to make use ofopendirandreaddirto traverse the directory, simulating a simplels.

/* listdir.c */
#include <stdio.h>
#include <dirent.h>

int main (int argc,char *argv[]) {
    int total = 0;
        DIR *pDir;
        struct dirent *pDirent;

        if (argc < 2) {
            printf ("Missing out directory!\n");
            return -1;
        }
        pDir = opendir (argv[1]);
        if (pDir == NULL) {
            printf ("Cannot open directory '%s'\n", argv[1]);
            return 1;
        }

        while ((pDirent = readdir(pDir)) != NULL) {
            printf ("[%s]\n", pDirent->d_name);
        }
        closedir (pDir);
        return 0;
    }

When you run the command `./listdir .',

The content of the current directory is printed.