Question: I want to create a directory if it does not exist already.

Is using the `is_dir` function enough for that purpose?

```
if ( !is_dir( $dir ) ) {
    mkdir( $dir );       
}

```

Or should I combine `is_dir` with `file_exists`?

```
if ( !file_exists( $dir ) && !is_dir( $dir ) ) {
    mkdir( $dir );       
} 

```

Answer: 
```
$dirname = $_POST["search"];
$filename = "/folder/" . $dirname . "/";

if (!file_exists($filename)) {
    mkdir("folder/" . $dirname, 0777);
    echo "The directory $dirname was successfully created.";
    exit;
} else {
    echo "The directory $dirname exists.";
}

```
This is an old, but still topical question. Just test with the `is_dir()` or `file_exists()` function for the presence of the `.` or `..` file in the directory under test. Each directory must contain these files:

```
is_dir("path_to_directory/.");    

```