Similar features of c and c plus plus?

Answer 1

The similar features of C and C++ is C itself. C++ is a superset of C, thus every C program is (or can be) a valid C++ program. C++ is more consistent and stricter than C, however, so some C programs may need some minor alterations in order to become C++ compliant. For that reason it is simpler to enumerate the differences than it is to enumerate the similarities.

The following list enumerates all the differences with respect to a C programmer compiling C code under C++.

1. In C++, assigning from void* is not permitted -- you must use an explicit cast.

int *x = malloc (sizeof (int) * 10); // C version

int *x = static_cast<int*>( malloc (sizeof (int) * 10)); // C++ version

2. In C++, a function MUST be declared before it can be used. Although most C programs do follow this convention, it is not strictly enforced.

3. In C++, we cannot invoke the main function from within another function of the same program.

4. In C++, main must return an int, however return 0 is implied if not explicitly stated at the end of the function.

5. In C++, multiple declaration of global variables is not permitted.

Provided a C programmer adheres to these conventions, the program will compile under C++. Everything else in C is fully compliant with C++.