lecture 5

Question 1

what is a constructor?

Answer 1

• its a public member function
• A constructor’s name must be the name of the class
• A constructor cannot return a value No return type, not even void, is used in declaring or defining a constructor
• A constructor is automatically called when an object
  of the class is declared
• can be used to initialize member
  variables when an object is declared

Question 2

how do we call constructors?

Answer 2

A constructor is called in the object declaration

exampe:-

BankAccount account1(10, 50, 2.0);

// Creates a BankAccount object “account1” and calls the
constructor to initialize the member variables

Question 3

a ……….constructor doesnt have parameters

Answer 3

default

Question 4

The default constructor is called during
declaration of an object An argument list is not used

which call is legal and which is not ?

• BankAccount account1;
• BankAccount account1( );

Answer 4

BankAccount account1;
// uses the default BankAccount constructor

while,
BankAccount account1( );
// Is not legal

Question 5

what is an initialization section ?

Answer 5

An initialization section in a function definition
provides an alternative way to initialize
member variables

example:-

• BankAccount::BankAccount( ): balance(0),
  interest_rate(0.0);
• BankAccount::BankAccount(int dollars, int cents, double rate)
  : balance (dollars + 0.01 * cents),
  interest_rate(rate)

NOTE : the parameters could be arguments in the initialization section

Question 6

Class operations are typically implemented
as ……………….

Answer 6

• member functions

Question 7

when we want to implement a function that is not a member of a class we use ……………..like:-
…………..and ………and ………….

Answer 7

• public accessor functions like getters and settters and friend functions

Question 8

what is a friend function?

Answer 8

• frriend functions are NOT members of a class, but
  can access private member variables of the class
• A friend function is declared using the keyword
  friend in the class definition

Question 9

A friend function is declared as a friend in the
……………..
◼ A friend function is defined as a nonmember
function WITHOUT using the “::” operator
◼ A friend function is called WITHOUT using the
‘.’ operator

Answer 9

• class definition

Question 10

Friend functions can be written as non-friend
functions using the …………………that should be part of the class

Answer 10

normal accessor and mutator
functions

Question 11

use a …………… if the task
performed by the function involves only one object

use a……………. if the task
performed by the function involves more than
one object

Answer 11

• member function
• nonmember function (that could be a friend function )

Question 12

difference between call by value paraeter and call by reference parameter??

Answer 12

call by reference parameter is MORE efficient because there is only 1 copy of the argument as the parameter here acts as a place holder replaced by the argument .

A call-by-value parameter LESS efficient because the parameter is a local variable initialized to the value of the argument this results in two copies of the argument

Question 13

To “mark” a call-by-reference parameter so it
cannot be changed:
◼ Use the modifier ……. before the parameter type
◼ The parameter becomes a constant parameter
◼ const used in the function-……….. and ………..

Answer 13

• const
• declaration and definition

Question 14

To declare a function that will not change the
value of any member variables:
◼ Use const after the parameter list and
just before the semicolon

example :-

void output (ostream& outs) const ;

Answer 14

To define a function that will not change the
value of any member variables:
◼ Use const in the same location as the function
declaration

example :-

void Money :: output(ostream& outs) const
{
// lines
}