Sams Teach Yourself C++ in 21 Days

Answers 835

D

Day 9

Quiz ................................................................................................................

1. A reference is an alias, and a pointer is a variable that holds an address. References
   cannot be null and cannot be assigned to.


2. When you need to reassign what is pointed to, or when the pointer might be null.


3. A null pointer (0).


4. This is a shorthand way of saying a reference to a constant object.


5. Passing byreference means not making a local copy. It can be accomplished by
   passing a reference or by passing a pointer.


6. All three are correct; however, you should pick one style and then use it
   consistently.

Exercises ........................................................................................................

1. The following is one possible answer:
   1: //Exercise 9.1 -
   2: #include
   3:
   4: int main()
   5: {
   6: int varOne = 1; // sets varOne to 1
   7: int& rVar = varOne;
   8: int pVar = &varOne;
   9: rVar = 5; // sets varOne to 5
   10: pVar = 7; // sets varOne to 7
   11:
   12: // All three of the following will print 7:
   13: std::cout << “variable: “ << varOne << std::endl;
   14: std::cout << “reference: “ << rVar << std::endl;
   15: std::cout << “pointer: “ << *pVar << std::endl;
   16:
   17: return 0;
   18: }


2. The following is one possible answer.
   1: int main()
   2: {
   3: int varOne;
   4: const int const pVar = &varOne;
   5: varOne = 6;
   6: pVar = 7;
   7: int varTwo;
   8: pVar = &varTwo;
   9: return 0;
   10: }

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