Name: __________________

Quiz 6 (Week 7)

CS-150, Fall ‘02, Dr. C. S. Tritt

Each of the following 2 questions is worth the same amount.

1. What output would the following fragment of C++ code produce (assume any necessary header files have been included and variables declared and defined)?

double pole(double a, double b, double c, bool& f)

{

if (b == c)

{

f = false;

return 0.0;

}

else

{

f = true;

return a/(b-c);

}

}

int main()

{

bool flag;

double x = 3.;

double y = 2.;

double z = 1.;

cout << "Working... ";

double result = pole(x, y, z, flag);

if (flag) cout << "Result 1 is " << result << endl;

z = 2.;

cout << "Working... ";

result = pole(x, y, z, flag);

if (flag) cout << "Result 1 is " << result << endl;

cout << "All done.\n";

return 0;

}

Answer –

Working... Result 1 is 3

Working... All done.

Display second result –15, forgetting All done –5, displaying Result… true or false –25, new lines not counted.

2. Write a fragment of C++ code that defines a type double function called poly that evaluates the expression y(x) = x² + x – 1 where x is a type double. For example, the call poly(3.0) would return the value 11.0.

Answer –

double poly(double x)

{

return x*x + x - 1;

}

Defining variables twice –5, not returning results –10, I/O in function –20, extra arguments –10 and returning wrong value –5.