Simple Variables in Java & C++

Question

I saw this sentence in some matrials:

"In Java, simple data types such as int and char operate just as in C."

I am wondering that actually they are different in Java & C++?

In C++, simple variables like the primitives in Java are assigned a memory address as well, so these primitive types in C++ can have a pointer as well. However primitives in Java are not assigned a memory address like Objects are.

Am I correct?

Thanks!

Answer 1

Almost.

In java primitives are assigned memory as well, but this happens internally and you cannot get the reference.

Thre reason was to provide security on memory management.

Answer 2

Primitives are stored onto the Stack and are passed by value.

int x = 5;
int y = x;

y++;

// y = 6
// x = 5

Objects are stored onto the heap and are passed by reference.

Object a = new Object();
Object b = a;

b.someAction();

// A and B point to the same object and both have had the 'someAction()' performed

I've no idea if this is what your asking, but I'm bored and wish to post something

Answer 3

See http://stackoverflow.com/questions/564/what-is-the-difference-between-an-int-and-an-integer-in-javac

Answer 4

There are a few differences between Java and C++ when it comes to simple types. The memory allocation is different as Java hides the concept of explicit pointers and references. You just create the simple type and assign a value. Another difference is that Java uses standardized memory footprints for each simple type check Java Simple Types. C++ on the other hand is dependent on the platform that it is compiled on. Another point (and I don't know if it is a difference or not) is that assignment into simple types is Thread safe. I've not done any multi-threaded programming in C++ so I'm not certain if this is a consideration.

Answer 5

For most basic stuff, they work the same, but there is a ton of detail differences.

• There are no unsigned numerical types in Java (except char, which technically but not semantically numerical)
• Java's "primitive types" can only live on the stack (as local variables) or inside objects on the heap, but not directly on the heap.
• The char type is very different - in C, it's defined to contain one byte (the byte may or may not have 8 bits), whereas in Java, it's defined to be 16 bit.