1. Structures allow grouping of different data types under a single name and are user-defined types in C++. They contain data members and may have functions associated with them. 2. Unions are similar to structures but can hold only one data member at a time and share the same memory location for all members. 3. Classes are like structures but can contain data members and functions together. They are the basis for object-oriented programming in C++.

7. rollno name 10 11 12 13 14 15 16 17 18 19 0 1 2 3 4 5 6 7 8 9 20 21

11. void main () { union student S1; // Union variable printf( “Input the name of student “ ); scanf( “%d” ,&S1.name); printf( “Input the Roll number of student “ ); scanf( “%d” ,&S1.rollno); printf( “name =%d“ S1.name); printf( “Roll number=%d“ S1.rollno); getch(); }

13. name rollno 10 11 12 13 14 15 16 17 18 19 0 1 2 3 4 5 6 7 8 9