# 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, namely`DIR`and`dirent`.

`DIR`is a structure for directory streams, and`dirent`has the following members:

* `ino_t d_ino`

  : file serial number
* `char d_name[]`

  : Name of entry.

## Example <a href="#example" id="example"></a>

In the following, we try to make use of`opendir`and`readdir`to traverse the directory, simulating a simple`ls`.

```c
/* 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 .',

![](https://2015623591-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-Lp-5TQpuuM0wVgRDmqL%2F-Lp-5WZ7mVLwEZ2xvCJW%2F-Lp-6Ly2cflMNPZGyS8c%2Flistdir.png?generation=1568738740094732\&alt=media)

The content of the current directory is printed.