C++ vs. The Arduino Language?

My personal experience as professor (programming, mechatronics) is that if you have previous programming experience and you are aware of concepts as OOP, it is better to go for C/C++. The arduino language is really great for beginners, but have some limitations (e.g. you must have all your files in the same folder). And it is basically a simplification of C/C++ (you can practically copy&paste arduino code to a C/C++ file, and it will work). Also it makes sense that you can go and use a full well known IDE as eclipse:

http://playground.arduino.cc/Code/Eclipse

Initially it is required a bit more of setup and configuration of your dev environment, but IMHO it is worth it for programmers with experience in any other language.

In any case, it won't harm you to start using the arduino language and the arduino IDE for a few days to get familiar with the arduino hardware and then move to C/C++ with Eclipse for really developing your project.

In theory...
There isn't really an Arduino language as such. It's really just C++ with some domain-specific libraries. These add on various features, such as functions you can call to control the hardware. If you didn't have those functions, you'd need to fiddle directly with special registers to control everything. That's how embedded programming is usually done. It's fast, but it can be quite hard to learn and understand.

In addition to the functions, the libraries add alternative names for some types. For example, boolean and byte are not in the C++ standard. However, they are directly equivalent to bool and unsigned char.

All of these things mean you can probably port general C++ code directly to Arduino without difficulty. However, going back the other way may require some minor editing.

In practice...
Having said all of that, programming for Arduino isn't exactly the same as general C++ programming. A lot of the differences are common to all embedded programming though (such as limited memory and processing power).

It's also worth noting that if you're using the official Arduino IDE then there are all sorts of annoying quirks and limitations on how you setup your code. There are workarounds in all cases (as far as I'm aware), but they are sometimes quite frustrating.

For full flexibility, use a third-party IDE (such as Eclipse) with a plug-in to support Arduino. That should give you all the advantages of C++, along with the Arduino libraries.

What are the advantages of C++ vs the Arduino language when using Arduino? I'm experienced in preprocessed languages like JavaScript, PHP, and have fiddled with languages like Java and Visual Basic.

First, the Arduino compiler/IDE accepts C and C++ as-is. In fact many of the libraries are written in C++. Much of the underlying system is not object oriented, but it could be.

Thus, "The arduino language" is C++ or C.

C++ is not garbage collected. It does manage variables in scope - if you write:

int led = 13;

void blinkTimes(int value)
{
   int i;

   for(i=0;i<value;i++)
   {
      digitalWrite(led, HIGH);
      delay(1000);
      digitalWrite(led, LOW);
      delay(1000);
   }
}

Then you'll find that led and i don't grow or leak, no matter how many times you call blinkTimes.

If i were a class, it would similarly be disposed of once the function ended. So as long as you aren't using new or similar memory allocation functions to create new objects, then you won't have to worry about leaks.

You may still run out of memory, if you create huge classes and use a lot of them in deeply nested functions, but in general you aren't going to run into trouble until you start dealing with new and free functions.

If you are using new, then you'll have to call delete at appropriate times. C++, and by extension Arduino, has no automatic garbage collection, you have to explicitly manage your own memory.