How do java statements differ from c nd c plus plus?

Answer 1

There's little point in trying to compare Java statements to C statements since C is not an object-oriented language. There are some obvious similarities, however that is only because the Java language borrowed heavily from the C++ language, while C++ evolved directly from C. Other than that, Java and C have nothing in common whatsoever.

Java and C++ are both object-oriented languages, however Java is 100% object-oriented. C++ is largely object-oriented, but because it inherits from C it also inherits all of C's fundamental data types such as int, char and, more importantly, pointer variables. Java has none of these -- everything is implemented as an object.

One key difference between Java and C++ is that, by default, objects are passed to functions by reference in Java. In C++, all variables are passed by value by default. Although it makes more sense to pass by reference, C++ must retain backwards compatibility with C, which has no concept of references whatsoever (to pass by reference in C you must pass by pointer -- but the pointer itself is passed by value). You can, of course, pass by reference in C++ using C++ references (which C does not support), but it is not by default -- that's the key difference.

Another key difference is that in Java all class methods are virtual by default. In C++, all methods are non-virtual by default. In some ways, defaulting to virtual makes a lot of sense and perhaps, with hindsight, C++ would have done the same. It's certainly a lot easier to mark a derived class as final in Java, whereas in C++ you have to manipulate the language to achieve the same end.