Difference between structure and class

Answer 1

Structure members are public by default while class members are private by default. Classes encapsulate the data and the methods that operate upon that data into a discrete package (an object), exposing only as much or as little interface as is required by the class itself, to ensure the data remains in a valid state at all times. Structures have no such protection.

Answer 2

In C++ there is no difference other than default access. Struct members are public by default while class members are private by default. As such, the following definitions are equivalent:

class C {

int data; // implicitly private

};

struct S {

private:

int data; // explicitly private

};

By convention we use a struct to define a POD (a plain old data type), the equivalent of a struct in C, and use a class to define a C++ type.