<p>I've been seeing that expression for over 10 years now. I've been trying to think what it's good for. Since I see it mostly in #defines, I assume it's good for inner scope variable declaration and for using breaks (instead of gotos.)</p>
<p>Is it good for anything else? Do you use it?</p>

It is a way to simplify error checking and avoid deep nested if's.  For example:
```
```
do {
  // do something
  if (error) {
    break;
  }
  // do something else
  if (error) {
    break;
  }
  // etc..
} while (0);
```
```