What is the default file read/write location?
<p>Whenever I write to a file (using methods such as `NSArray writeToFile:atomically:", I first use:</p>

<pre><code>NSString* rootDir=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString* fileName=[rootDir stringByAppendingPathComponent: @"my_file_name"];
</code></pre>

<p>Where is the file written to if I just write to <code>@"my_file_name"</code> instead?</p>
