Department of Computer Science
University of Illinois at Urbana-Champaign
Computer Science 101: Mid Term Exam II (60 minutes)
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Name: NetID:
Lab Section: Date: November 6th, 2008
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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 11 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. For your own protection, in case pages come apart, write your NetID at the TOP of each page before beginning work.
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. 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 |
Deduction |
Grader |
|
8 |
|
|
|
|
2 |
8 |
|
|
|
3 |
10 |
|
|
|
4 |
6 |
|
|
|
5 |
8 |
|
|
|
6 |
6 |
|
|
|
7 |
6 |
|
|
|
8 |
6 |
|
|
|
9 |
6 |
|
|
|
10 |
19 |
|
|
|
11 |
10 |
|
|
|
12 |
8 |
|
|
|
13 |
5 |
|
|
|
14 |
5 |
|
|
|
15 |
14 |
|
|
|
Total |
125 |
|
|
|
|
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Exam Scoreà |
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A
Use the figure below for the next three questions. Assume that your home directory is pictured as in the figure below. Thus, your home directory contains a file named cat.txt, and also contains the directories named lab9 and workspace; the directory lab9 contains the files named lab9.c and a.out; the directory workspace contains a directory named lab10.
1.
Assume that you are in the lab10
directory. Write a single Unix command to change the directory to
your home directory.
_______________________________________________________________
2.
Assume that you are in your home
directory. Write a single Unix command to rename the file named cat.txt
to the file named dog.txt .
_______________________________________________________________________
3.
Assume that you are in your home
directory. Write a single Unix command to copy all the
contents of the directory named lab9
into the lab10 directory.
________________________________________________________________________
4. The following C program compiles and runs without errors. Write the output produced by this program.
#include <stdio.h>
void main(void)
{
/* printf("This is a comment."); */
printf("That was a comment.\n");
}
________________________________________________________________________
5. The following C program compiles and runs without errors. Write the output produced by this program.
#include <stdio.h>
void
main(void)
{
int x = 5;
int y = 4;
int z = 0;
if ((x < 1) || ( y > 3))
printf("H ");
if ((x > 4) && (y < 3))
printf("I ");
else
printf("J ");
if ( !(x < 2))
printf("K ");
if (z)
printf("L ");
else
printf("M ");
printf("\n");
}
_______________________________________________________________
6. The following C program compiles and runs without errors. Write the output produced by this program.
#include <stdio.h>
void main(void)
{
int i = 2;
if (i/3 == 0)
{
switch(i/2)
{
case 3: printf("A ");
case 2: printf("B ");
case 1: printf("C ");
default: printf("D " );
}
if (i == 2)
printf("E " );
else
printf("F " );
}
else
{
switch(i/2)
{
case 3: printf("U ");
case 2: printf("V ");
case 1: printf("W
");
default: printf("X " );
}
if (i == 2)
printf("Y " );
else
printf("Z " );
}
}
_______________________________________________________________
7. The following program compiles and runs without errors:
#include <stdio.h>
void main(void)
{
int c = 7;
char n = 'c';
int i = 1;
printf("\n i %i n %c c %i n \n",i,n,c);
}
Which of the following is the output obtained after running this program?
Circle the correct answer. (There is only one correct answer below.)
a) Hello, world!
b) 1 1 c c 7 7 c
c) i %i n %c c %i n 1 c 7
d) \n i %i n %c c %i n \n 1 c 7
e) i 1 n c c 7 n
8. Which of the following is a correct way of reading an integer value from the keyboard and storing the value in a variable named c (assuming c has been previously declared as having type integer)? Circle the correct answer. (There is only one correct answer below.)
a)
scanf("%i",c);
b)
scanf("&i",c);
c) scanf("&i",%c);
d)
scanf("%i",&c);
e) scanf(c,"%i");
9. Assume that a C program contains the following line, where x, y and z are previously declared integer variables:
x * z = y;
Circle the correct answer. (There is only one correct answer below.)
a)
The above is a correct C statement that
assigns the value of y to the result of multiplying x and z.
b)
The above is incorrect, since a
compound expression cannot be specified in the left-hand side of an assignment
in C.
c)
The above is a correct C statement that
assigns to y the result of multiplying x and z.
d) The above is a correct C statement that multiplies x with the result of assigning z to y.
10. Complete the following C program by filling in the blanks
below. When your program runs it should produce the output exactly as shown
below.
#include <stdio.h>
void main(void)
{
int mat[ 3 ] [ ___ ] = { __________________________________________________ };
int i, j;
/* This code just prints the matrix */
for(i = _______; ___________ ; _______)
for(j = _______; ___________ ; _______)
{
printf("_______", _______________);
if( j == _______________)
printf("\n");
}
}
11. The following C program compiles and runs without errors. Write the output of this program.
#include <stdio.h>
#include <string.h>
void main(void)
{
char temp[32];
char vegetable1[32] = {'P', 'E', 'A', 'S', '\0'};
char vegetable2[32] = {'C', 'A', 'R', '\0', 'O', 'T', 'S', '\0'};
printf("%s \n", vegetable1);
printf("%s \n", vegetable2);
vegetable2[3] = 'R';
strcpy(temp, vegetable2);
strcpy(vegetable2, vegetable1);
strcpy(vegetable1, temp);
printf("%s \n", vegetable1);
printf("%s \n", vegetable2);
if (strcmp( vegetable1, vegetable2) == 0)
printf("yes \n");
else
printf("no \n");
}
_______________________________________
_______________________________________
_______________________________________
_______________________________________
_______________________________________
12. Circle each C loop below that terminates, i.e., does not repeat infinitely. Assume that n is a variable of type int.
a) for (n = 1; n < 40; n *= 2)
if (n == 37)
break;
b) for (n = 100; ; n = n + 1)
if (n % 500 == 0)
break;
c) n = 5;
while (n != 0)
{
n = n - 2;
if (n < -4)
n = 5;
}
d) n = 1;
do
{
printf("%i ", n);
n = 5;
} while (n >= 4);
13. The following C program compiles and runs without errors. Write the output that it produces.
#include <stdio.h>
void main(void)
{
int j, A[5];
A[0]=0; A[1]=1;
for (j=2; j<5; j++)
A[j] = A[j-1]+A[j-2];
for (j=4; j>=0; j--)
printf("%i ", A[j]);
}
______________________________________________________________________
14. Circle each answer choice whose code fragments produce the output 1 4 9 (if included in a complete C program which compiles and runs without errors). Assume that n and k are variables of type int.
a) for (n = 1; n <= 3; n++)
printf("%i ", n*n);
b)
k
= 0;
for (n = 0; n
<= 2; n++)
{
k = k+2*n+1;
printf("%i ", k);
}
c) for (n = 1, k = 0; n <= 3; n = n + 2)
{
k = k + n;
printf("%i ", k);
}
d) for (n = 1; n <= 3; n++)
{
for (k = 0; ; k++)
if (k*n == n*n*n)
break;
printf("%i ", k);
}
e) k = 0;
for (n = 2; n <= 4; ++k, ++n)
printf("%i ", k*n+1);
15. Complete the following C program by filling in the blanks. This program should prompt the user to enter a positive integer and next read that integer into the variable named h. Then the program should print out a triangle of height h. For example, if h equals 6 then your program should print a triangle in the following shape:
1
1 2
1 2 3
1 2 3 4
1 2 3 4 5
1 2 3 4 5 6
Of course your code should work correctly for any height not only for the one shown above.
#include <stdio.h>
void main(void)
{
int h, row, col;
printf("Enter the height of the triangle: ");
scanf(" _________", ___________);
for(row=1; row <= ________ ; ++row)
{
for(col= ______ ; ________________ ; ++col)
printf("%i ", ___________________);
printf( __________ );
}
}