C++ provides a mechanism to ensure that a given function is limited to throwing only a specified list of exceptions. It is called as exception specification.

Structure: Initially (in C) a structure was used to bundle different type of data types together to perform a particular functionality. But C++ extended the structure to contain functions also. The major difference is that all declarations inside a structure are by default public.
Class: Class is a successor of Structure. By default all the members inside the class are private.

The free subroutine frees a block of memory previously allocated by the malloc subroutine. Undefined results occur if the Pointer parameter is not a valid pointer. If the Pointer parameter is a null value, no action will occur. The realloc subroutine changes the size of the block of memory pointed to by the Pointer parameter to the number of bytes specified by the Size parameter and returns a new pointer to the block. The pointer specified by the Pointer parameter must have been created with the malloc, calloc, or realloc subroutines and not been deallocated with the free or realloc subroutines. Undefined results occur if the Pointer parameter is not a valid pointer.

ConstKeyword indicates that memory once initialized, should not be altered by a program.
Volatile keyword indicates that the value in the memory location can be altered even though nothing in the program.
Mutable keyword indicates that particular member of a structure or class can be altered even if a particular structure variable, class, or class member function is constant.

C requires all the variables to be declared at the beginning of a scope but in c++ we can declare variables anywhere in the scope. This makes the programmer easier to understand because the variables are declared in the context of their use.

All the features of C are similiar to C++ except some features, such as polymorphism, operator overloading which are supported in C++ but not in C language.

Both C and C++ language is similiar in their functionality but C++ provides with more tools and options.

Output: 1 1 1 1 1 1
For loop will execute six times.

Note: continue keyword in do-while loop bring the program its while condition (while(0)) which is always false.