600.109 INTRO TO PROGRAMMING IN C/C++			Spring

	ANSWERS for PRACTICE TEST 2 			


What is the exact output of each code segment?

->	cout.setf(ios::fixed);
	cout.setf(ios::showpoint);
	cout.precision(4);
	n1 = 1;
	while (n1 <= 3)
	{	r1 = pow(3,n1) / 8.0;
		cout << r1 << endl;
		n1++;
	}

0.3750
1.1250
3.3750
	
->  Write a code segment, including all variable declarations, to read and
    output the sum of a bunch of integers, until the end of input occurs.

int num, sum = 0;
while (cin >> num)
{	sum += num;
}
cout << sum << endl;

-> Standard input and output operators and functions (such as << 
	and >>) may be used with which type of external file?

	sequential text files (not random access)


-> All external files must be initialized with which ifstream function
	before it can be accessed in a program?

	open (or constructor with parameter)


-> Write a statement to create a stream for writing to an external text file
	called "outfile.txt".

	ofstream of("outfile.txt");


-> Given the following array, write the array as it exists in memory
	after the first pass of the outer loop of a SELECTION SORT.

	r = {17, 32, 1, 22, 5}

	after 1st pass:

	r = 1 32 17 22 5


-> Given the following array, write the array as it exists in memory
	after the first pass of the outer loop of a BUBBLE SORT.

	r = {17, 32, 1, 22, 5}

	after 1st pass:

	r = 17 1 22 5 32


-> Given the following array, what numbers would be looked at (in what
	order) during a BINARY SEARCH for the number 2?  (State any 
	assumptions you make about the search details.)

	r = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}

	assume div (truncate) to get middle index - (left of middle)
	8  4  2

	assume round up to get middle index (right of middle)
	9  5  3  2


-> Given the following array, what numbers would be looked at during a
	LINEAR SEARCH for the number 12?

	r = {23, 13, 29, 31, 20, 30, 12, 24, 90}

	23 13 29 31 20 30 12


-> If an array is sorted already, which type of search is faster: binary or
	linear?

	binary

-> If an array has N elements, what is the time complexity for a bubble sort?

	O(N^2)  (N squared)

-> What sorting algorithm is faster than a selection sort?

	mergesort, quicksort


-> What is the output of the following program?


/************************ ACTUAL PROGRAM *********************/
#include <iostream>

void funk1 (int, float);
int funk2 (double &, int);

int main() {
	const int m = 15;
	int	i, j, k;
	float	y;
	double	x, z;

	i=4;
	y=2.2;
	funk1(i, y);
	funk1(15, 0);

	k = 13;
	for (i=8; i<=20; i+=3)
	{	cout << i << ' ' << k << endl;
		k++;
	}

	x = 3;
	cout << "funk2: " << funk2(x,3) << endl;
	cout << "x: " << x << endl;
	z = 11.5;
	cout << "funk2 again: " << funk2(z,-2) << endl;
	cout << "z: " << z << endl;

	return 0;

} // end of main
	

void funk1 (int i, float x)
{	int count = 1;
	float result=0;

	while (count <= i)
	{	result += x;
		count++;
	}
	cout << result << endl;
}

int funk2 (double & num, int rep)
{
	int count = 0;
	do {
		num = num + 1.1;
		rep--;
		count++;
	} while (rep > 0);
	return count;
}


/**  OUTPUT

8.8
0
8 13
11 14
14 15
17 16
20 17
funk2: 3
x: 6.3
funk2 again: 1
z: 12.6

**/


-> Write a loop which prints the odd integers from 12 down to 3
	(including 3).  Include necessary variable declarations.

	for (int i=11; i >= 3; i -= 2)
	{
           cout << i <<"   ";
	}	
 
	// or

	int i = 12;
	while (i >= 3)
	{	if (i%2 == 1) cout << i << " ";
		i--;
	}



-> What is the output of the following program?

	#include <iostream>

	int main ()
	{	
		int ra[] = {5, 10, 15, 20, 25};
		doit(ra, 5);
	}

	void doit(int r[], int i)
	{	
		for ( ; i > 0; i--)
		{
			cout << r[i-1] << "  ";
		}
		cout << endl;
	}

================
25 20 15 10 5 
================

-> What is the output of the following program?

    #include <iostream>

    int main ()
    {
	const int MAX=4;
	char w[] = "spring fair";
	double	r[MAX];
	int	t[4][6];

	for (int i=0; i<MAX; i++) {		
		cout << i << ' ';
		r[i] = i*i;
	}
	cout << endl;

	for (int n=MAX-1; n>=0; n-=2)
		cout << r[n] << ' ';
	cout << endl;
	
	cout << w[5] << endl;		

	for (int k=0; k<6; k++)
	    for (int j=0; j<4; j++)
		t[j][k] = j + k;

	cout << t[2][1] << endl;	

	return 0;
    }

=========
0 1 2 3 
9 1 
g
3
=========