Department of Computer Science

University of Illinois at Urbana-Champaign

Computer Science 101: Mid Term Exam II (60 minutes)

Name: NetID:

Lab Section: Date: November 2, 2005

No questions will be answered during this examination. If you do not understand a question, read it again. If you still do not understand it, make reasonable assumptions and write them down. (Points will be deducted if unreasonable assumptions are made.)
DO NOT CHEAT: Cheating includes not only copying from another person but also allowing someone to copy from you. Anyone who copies or allows someone to copy will receive a score of zero. So be defensive and protect your work.

This examination contains 10 pages including this page. Check that your copy is complete, and ask for a replacement if it is not. Do all your work on these pages. The number of points for a question is roughly proportional to the amount of time you may need for it. Don’t spend too much time on any one question.

Do not forget to sign the attendance list and to write your signature on the line below:

_______________________________________________________________________
(If your exam is misplaced and you did not sign the attendance list then you will receive a zero score for the exam.)

You may not use any electronic devices, book, notes or other references during this examination.

DO NOT WRITE IN THIS SPACE

Section	Possible Score	Score	Grader
1	8
2	4
3	10
4	6
5	8
6	4
7	8
8	6
9	7
10	8
11	6
12	6
13	12
14	10
15	4
16	10
17	8
Total	125

A

1. You are in your Unix home directory. You have the following subdirectories:

subdirectory: files in it

------------- ------------

lab7 labsoln.c

lab8        guess.c
lab9 bandit.c

a) Assuming your pwd (current directory) is your home directory, write a single Unix command

to list all the contents of the lab7 directory.

ls lab7 OR ls –a lab7 OR ls ~/lab7 (other variations possible)

b) Assuming your pwd (current directory) is your home directory, write a single Unix

command to make the lab8 directory your current directory.

cd lab8 OR cd ~/lab8 (other variations possible)

c) Assuming that lab8 is your current directory, write a single Unix command to copy the file

bandit.c (located in the lab9 directory) into the lab8 directory. Do not change the

name of the file.

cp ~/lab9/bandit.c . OR cp ../lab9/bandit . (other variations possible)

d) Assuming that lab8 is your current directory, write a single Unix command to move the

file guess.c (located in the lab8 directory) into the lab9 directory. Do not change the

name of the file.

mv guess.c ~/lab9 OR mv ~/lab8/guess.c ../lab9 (other variations possible)

2. Using the Unix ls command and Unix redirection( > ), write a single Unix command to create a new text file named screen.txt (to be located in the current directory) that contains the names of all the other files in the current directory.

ls > screen.txt

3. Using nested if statements (or if-else statements), write C code that will produce the same output as the following switch statement. Your code may not include a switch statement. Do not write a complete C program. You may assume that x will only be assigned the three values: -1, 0, and 1.

switch(x){

case -1:

printf(“Negative\n”);

break;

case 0:

printf(“Zero\n”);

break;

case 1:

printf(“Positive\n”);

break;

}

if ( x == -1)

printf(“Negative\n”); if ( x == -1)

else printf(“Negative\n”);

if ( x == 0)

printf(“Zero\n”); if ( x == 0)

else printf(“Zero\n”);

if ( x == 1) (may omit if)

printf(“Positive\n”); if ( x == 1)

printf(“Positive\n”);

4. Write the value of i and j after the following loop is executed.

int i = 36, j = 3;

while(i != 0){

i -= 4;

j += 2;

}

i = _____________0___________________

j = ____________21______________________

5. The following C program compiles and runs without errors. Write the output of this program.

#include <stdio.h>

void main(void){

int no = 1, v = 0;

int a = 4;

switch ( no ) {

case 1: v = v - 5;

case 2: v = v - 3;

break;

case 3: v = v + 1;

default:

printf("%i " , no);

}

printf("%i \n", v);