OBJECT-ORIENTED DESIGN 273-422 Midterm Exam 2 hours

 

There are 4 questions. The percentage of marks is indicated for each question.

 

NAME: ______________________________ STUDENT #: __________________

 

 

 

[20] 1. Write a C++ function 'print_pattern() which uses nested 'for' loops

to display patterns like the following:

 

                                    1

                                    1 2

                                    1 2 3

                                    1 2 3 4

                                    1 2 3 4 5

                                   

            The function should take one integer parameter which is the number

            of lines to be printed (e.g. 5 to produce the above pattern).

            Note: no main() function is required for this question.

 

 

 

 

[25] 2. What would be printed by the following C++ program ?

 

            #include <iostream.h>

                       

            int        calc( int n )

            {

                        static int sum = 0;

                                   

                        sum += n;

                                   

                        if ((n++ % 2) == 0)

                                    return (sum);

                        else

                                    return (sum + 1);

            }

                       

            int        main( void )

            {

                        cout << calc( calc(5) ) ;

                        return 0;

            }

 

[35] 3. Write a C++ function which, given an array of integers (range: 0-100) representing the marks of a class of programming students, calculates the average mark and two other pieces of information: the number of students who failed (mark less than 50), and the number of students who got A (mark 80 or more).

This function should be called 'marks', should be of return type 'void' and have 5 parameters:

The 2 input parameters to this function should be the array of marks and the number of elements in that array.

The 3 pointer output parameters to this function should be the average mark, the number who failed, and the number who got A.

(Do not use global or file-scope variables. Do not use reference parameters. This function should not print anything.)

Note: the average of a set of values is the sum of those values divided by the number of values.

Note: you are just asked to write this function, not a whole program, so no main() function is required.

 

 

 

[20] 4. The following C++ program has at least 9 errors (syntactic, semantic, etc).

Indicate the errors by circling them (where appropriate) and giving a short explanation of what is wrong.

 

            #include <iostream.h>

            #include <string.h>

 

            int        main( void )

            {

                        char       buffer[10] = "dictionary",

                                    ptr; /* an abbreviation for pointer */

                        double   num1;

 

                        ptr = buffer;

 

                        while ( *ptr != '0' ) ;

                        {

                                    double   num2;

 

                                    num2 = strlen( ptr );

 

                                    cout << divide( num1, num2 ) ;

                                    ptr++;

                        }

 

                        return ( num2 );

            }

 

            static     double   divide( double a, b )

            {

                        if ( b != 0.0 )

                                    return ( a / b );

            }