August 1999
OP216 : OBJECT ORIENTED PROGRAMMING

QUESTION 1 (Compulsory)

Total Marks: 20 Marks

• Question 2
• Question 3
• Question 4
• Question 5
• Cover Page

SUGGESTED SOLUTIONS
Solutions and allocated marks are indicated in green.
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(ii) Describe one disadvantage of using the object oriented approach to programming.

[2]

• New data types can be created by inheriting from existing types;
• Thus promoting reuse and more reliable code.

• Object oriented languages require more run time checks;
• which can result in a program running slower.

(ii) Define a class called Triangle, which contains three private member integer variables, called side_a, side_b and side_c, which represents the sides of the triangle. Your class should also contain a default constructor and a default destructor.

(iii) Assume your Triangle class contains another constructor function, which instead takes three parameters. Give the O-O name for this situation.

[3]

[1]

• as we can restrict access to data and methods
• to the object itself
• or to other objects

class Triangle {
public:
    Triangle ( );

    ^~Traingle ( );

private:
    int side_a, side_b, side_c
} ;

(ii) Write a function which takes an array of characters and an integer specifying the length of the array, and reverses the order of characters in the array.

• In passing by value, changes are not reflected in the calling code;
• In passing by reference, changes are reflected in the calling code;

void reverse (char a[ ], int n) {
    for(int i= 0; i< n/2; i+) {
       char m;
       m= a [i];
       a[i]= a[n-i-1];
       a[n-i-1]= m;
    }
}