I am not able to understand the following points in regard to difference between C and C++,
1.The comma operator can result in an "l-value" (a quantity that can be used for the left-hand side of an assignment) in C++, but not in C.
2.Enumeration constants (enum values) are always of type int in C, whereas they are distinct types in C++ and may have size different from that of int.
3.C++ identifiers are not allowed to contain two or more consecutive underscores in any position. C identifiers are not allowed to start with two or more consecutive underscores, but may contain them in other positions.
4.In both C and C++ one can define nested struct types, but the scope is interpreted differently (in C++, a nested struct is defined only within the scope/namespace of the outer struct).
5.C allows struct, union, and enum types to be declared in function prototypes, whereas C++ does not.
6.A struct, union, or enum declaration in C++ is a first class type, while in C it is not.
Can anyone explain , some if not all, with examples.Thanks in advance