Question

1) Short Answer: a) Explain why a reference cannot be NULL (as opposed to a pointer which can be NULL). (2 points) b) Argue how the type of the variable (as static) results in the final value as 595, not 599. (3 points) int & examplebC) static int x - 599; return x; int mainC exampleb O 595; cout <examplebO; return 0 c) What is boxing/unboxing in programming? (2 points) d) Explain the motivation behind C++ "inline" functions. (3 points) e)Explain whatC++ Functors are and the motivaionbehind them. (4 points)

Answer 1

• a) Pointers is null which means it points to nothing.variables can be declared as a reference.Its like another name of a variable.
  Example - int x = 10; this is a variable
  while  int &ref = x ; this is a reference .
  If we change the value of reference, value of variable also changes,
  ex - ref=20; this means now x also contains 20.
  Reference cannot be changed once created, and you can not create a reference of something which is not even there i.e. null, hence reference cannot be null, but pointers can, this is the reason we use pointers to implement linked list and not references.
• b) when a variable is declared static the memory allocated to it is gets allocated to it for the lifetime of the program.Even if you call function multiple times , space allocated to x is same which is 599.It always restores it previous state no matter how many times you change it. In above example when cout<<emapleb() was done, it restored it orignal state which was 599 and not 595.
• Boxing is converting a value type to type object,and unboxing is converting object type to type value.
  example -
  int i = 3;
  object o = i; // Box converting int type to object
  int j = (int) o; //UnBoxing converting object to int type
• Functions are used to remove code duplicacy, suppose you want to check if 10 numbers are prime, if functions are not used you need to check each and every number 10 times,whether it is prime or not, which increases number of lines of code ,and also decreases code readability, instead we can create a function checkPrime(int n) which accepts a number and returns true/false checking if a number is prime or not. Hence functions are really important to improve code readability.