Difference between break and continue in PHP?

break ends a loop completely, continue just shortcuts the current iteration and moves on to the next iteration.

while ($foo) {   <--------------------?
    continue;    --- goes back here --?
    break;       ----- jumps here ----?
}                                     |
                 <--------------------?

This would be used like so:

while ($droid = searchDroids()) {
    if ($droid != $theDroidYoureLookingFor) {
        continue; // ..the search with the next droid
    }

    $foundDroidYoureLookingFor = true;
    break; // ..off the search
}

This is pretty language-specific. You seem to be mixing a fair share of both C++ and C#, both of which are very different languages (despite superficial similarities in syntax).

In C++ structs indeed default to public member visibility while class defaults to private. In C# struct is used to declare value types which are passed by value (note that the stack allocation is an implementation detail, not a contract).

Generally both languages seem to have the same idea of what struct and class should represent: struct is for simple data structures which do little more than holding data, while classes have state and methods to manipulate it. They are used to build objects in some concrete or abstract sense while data structures are just that: data in a structured form; they don't need to do much with that data or even know what data that is. Essentially they're dumb and don't care.

But that's just how the language designers thought they should be used. People are good at mis-using things so not every struct you see may be a simple, dumb data structure and not every class you see may be a full-blown class with lots of methods and whatnot. It's merely a convention and if people follow it others can look at the code and see "Oh, nice, that's a struct so I don't expect much logic here and move on to more interesting things." It might work ... in theory.

ETA: Since you mentioned in a comment that you are particularly interested in PHP or Java: Both languages do not have any distinction at the syntax or language level of class or struct which is why your question strikes me as a little odd. In both Java and PHP you model things as classes, regardless of whether they are just data structures without logic or actual classes with everything there is.

Never used any of those, but they look interesting..

Take a look at Gearman as well.. more overhead in systems like these but you get other cool stuff :) Guess it depends on your needs ..