Computer Science 2015

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Page 1 PLEASE TURN OVER

The University of the West Indies Course code: COMP1105 May 2015

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DO NOT WRITE OR TYPE ON THE BACK OF THIS SHEET: USE ONE SIDE ONLY

INSTRUCTIONS: Each page must be signed by the FI RST AND SECOND EXAM INERS. Completed forms should be

handed to the Assistant Registrar (Examinations).

.. ........... ................................... ............................................First Examiner Second Examiner

Date: 2015/04/…. Date: 2015/04/....

THE UNIVERSITY OF THE WEST INDIES

EXAMINATIONS OF May 2015

Code and Name of Course: COMP1105 - COMPUTER PROGRAMMING 1

Date and Time: Duration: 3 hours

INSTRUCTIONS TO CANDIDATES: This paper has 9 pages and 4 questions

All Questions are Compulsory

Marking Code:

Tests acceptable and basic knowledge of the material = 31.5

Tests applied skills and critical and analytical thinking = 21.5

Tests excellent skills and breadth of knowledge = 7

Question 1 [15 marks] (8 marks + 5 marks + 2 marks)

You are being interviewed as a contract programmer for the Faculty of Science and Technology.Your responsibility is to create simple, suitable, and secure games for students enrolled in

summer school to play in labs as a means of relaxation in the intense six week schedule of

summer school, in the down periods between classes and lab sessions.

Note: Read the entire question before you begin.

The interviewers ask you to write pseudocode (in 45 minutes) for a simple guessing game. Writeyour solution all in one program. All of the necessary preamble and concluding logic for an

algorithm is expected.

[2 marks]

a. In this game you have to start by printing a grid with a title as follows:

“THE GRID OF GUESSES

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| | | | |


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_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ”

Call a function (sub-program) with at least one loop in it to print the layout of the grid.

[3 marks]

b. Then print the following message:

“Welcome to the guessing game. You have 25 tries to guess the number that I am

thinking of between 1 and 30. Each time you make an incorrect guess, we willshow it to you in the GRID OF GUESSES. You may keep guessing until you are

successful or until you have filled the grid.”

The algorithm must then generate the number between 1 and 30 and not reveal it to the

user, ask the user to guess the number and then read the guess.

[2 marks]

c. The algorithm must check the guess against the generated number and if they are the

same it must print a message to the screen saying “Congrats, you have won!”, and then

stop the game.[2 marks]

d. If the guess is not correct, the algorithm must perform two tasks:

Print to the screen the incorrect guess in the grid in the next available spot.

Check to see if the guess is greater or less than the random number and indicate thisto the user.

[2 marks]

For example, if the random number is 17 and the player guesses 10, the following would be

printed to the screen:


10 | | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _Your number is too small. Try again”

If the player then guesses 20, the following would be printed to the screen:


10 |20 | | | | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _


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| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Your number is too big. Try again”

e.

Your algorithm must also keep score. Use a counter that starts at 25 and for everyincorrect guess, decrement it. The more guesses the less points. The user must be

restricted to 25 guesses.

[2 marks]Print your final score to the screen and to the file: myScores.txt.

[2 marks]

You do not have to use an array to hold the contents of the grid.

YOUR SOLUTION SHOULD INCLUDE DOCUMENTED PSEUDOCODE ONLY.

NO C-CODE IS REQUIRED.

SCHEME:BEGIN ALGORITHM (MAIN PROGRAM) [ ½ MARK ]

DECLARE [ ½ MARK ]

integer iSecretinteger iGuess,

integer array pos

integer guessesinteger points

File pointer fp to point to counter.txt

Initialize [[ ½ MARK ]Initialize pos to „\s‟ // can wor k because of ascii

Initialise guesses to 25

/*

a. In this game you have to start by printing a grid with a title as follows:“THE GRID OF GUESSES

| | | | | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _”

Call a function (sub-program) with at least one loop in it to print the layout of the grid.

*/

Call SubProgram PrintGrid [1/2 mark]


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print

“Welcome to the guessing game. You have 25 tries to guess the number that I am

thinking of between 1 and 30. Each time you make an incorrect guess, we will show it toyou in the GRID OF GUESSES. You may keep guessing until you are successful or until

you have filled the grid.”

// [1 mark]

/*

The algorithm must then generate the number between 1 and 30 and not reveal it to the

user, ask the user to guess the number and then read the guess.*/

iSecret Generate a random number between 1 and 20 // [1/2 mark]

print "Guess the number (1 to 30)” // [ ½ mark for request and read]

read iGuess

/*the algorithm must check the guess against the generated number and if they are thesame it must print a message to the screen saying “Congrats, you have won!”, and then

stop the game.

*/

[1/2 mark] [1/2 mark]

DO WHILE (iSecret NOT EQUAL iGuess) AND (guesses >= 0)

if iSecret EQUAL iGuess then // [ 1/2 mark]

print “Congrats, you have won” // [1/2 mark] exit program // [1/2 mark]

endif

/*10 | | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _Your number is too small. Try again”

*/

if iSecret < iGuess || iSecret > iGuess then [ ½ mark]increment guesses [ ½ mark]

pos [guesses] iGuess [ ½ mark]

decrement points // keep track of guesses and points [ ½ mark] print “

pos [0] | pos[1]| pos[2]| pos[3]| pos[4]| //etc. for all positions [ ½ mark]

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ pos [5] | pos[6]| pos[7]| pos[8]| pos[9]| //etc. for all positions


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_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

| | | | |

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ” if iSecret < iGuess then [ ½ MARK ] // HANDLE THE SMALL

print “Your number is too small. Try again”

if iSecret > iGuess then [ ½ MARK ] //HANDLE THE LARGE

print “Your number is too large. Try again”

print "Guess the number (1 to 30)” // [ ½ mark for request and read]

read iGuess

End WHILE //(iSecret NOT EQUAL iGuess) AND (guesses < = 25) // while they have not

// guessed correctly [1/2 mark]// and < 25 tries [1/2 mark]

open fp for writing [ ½ MARK ]

if fp EQUAL null [ ½ MARK ] print “error” [ ½ MARK ]

exit program

print “here are your points: points” to fp [ ½ MARK ]

End Algorithm [1/2 MARK ]

Begin Algorithm (SubProgram PrintGrid) // define function header [1/2 mark]

//use a loop correctly to do something in the grid patternFor i = 1 to 5 DO // print the five rows [½ mark]

For i = 1 to 5 DO [ ½ MARK ]Print “ |” // print tab and pipe pattern five times

EndFOR

For i = 1 to 5 DO [ ½ MARK ]Print “_ _ _ _ _” // pr int underline pattern 5 times

EndFOR

EndFOREnd Algorithm (SubProgram PrintGrid)

Question 2: Multiple Choice [15 Marks - 1 mark each] (9 marks + 6 marks)

i. Which of the following is not a valid C variable name?

a. int #number; b. float 1rate;

c. int main;

d. all of the above[1 mark]

ii. The format identifier „%lf‟ is also used for _____ data type?

a.

char b. int


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c. float

d. double

[1 mark]iii. What is the output of this C code if the input is 6, 8 and 10?

1. #include 2.

3. void main()4. {5. int num1, num2, num3;6.7. printf("Enter the values of num1, num2 and num3 ");8. scanf("%d %d %d", &num1, &num2, &num3);9. printf("num1 = %d\tnum2 = %d\tnum3 = %d\n", num1, num2, num3);10. if (num1 > num2)11. {12. if (num1 > num3)13. {14. printf("num1 is the greatest among three \n");15. }16. else

17. {18. printf("num3 is the greatest among three \n");19. }20. }21. else if (num2 > num3)22. printf("num2 is the greatest among three \n");23. else24. printf("num3 is the greatest among three \n");25. }Figure 1

a. num1 = 6 num2 = 8 num3 = 10 num3 is the greatest among three b.

num1 = 6 num2 = 8 num3 = 10

num3 is the greatest among three

c.

num1 = 6 num2 = 8 num3 = 10 num3 is the greatest among threed.

num1 = 10 num2 = 8 num3 = 6

num1 is the greatest among three

[1 mark]

iv. How many times will “True” be printed?

1. #include 2. int main()3. {4.

int i = 0;5.

while (i == 0);6.

printf("True\n");7.

printf("False\n");8.

}

a. Infinite times b. 1 time and then False

c. Never

d.

It depends


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[1 mark]

1. /* C program to check whether a given integer is odd or even*/

2.

3. #include

4.5. void main()

6. {

7. int ival, remainder;

8.

9. printf("Enter an integer : ");

10. scanf("%d", &ival);

11. remainder = ____________________; // 1

12. if (remainder == 0)

13. printf("%d is an _________ integer\n", ival); // 214. else

15. printf("%d is an _________ integer\n", ival); // 3

16. }

Figure 2

v. The C-code in Figure 2 above will check whether a given integer is odd or even. What

should be entered in the blanks?

a. (1) ival / 2 (2) even (3) odd b. (1) remainder % 2 (2) even (3) odd

c. (1) remainder % 2 (2) odd (3) even

d. (1) ival % 2 (2) even (3) odd[1 mark]

vi. The keyword used inside a loop to return to the beginning of the loop

a. Exit b.Goto

c.Continue d.Return

[1 mark]

vii. What will be the output of the code below?

a. dance (three spaces to the left of dance)

b. dance (followed by three spaces after dance)c. dance

d. *dance

[1 mark]#include int main(){

char s[8] = "dance";int i = 9;

printf("%*s", i, s);}


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viii. What will be the output value if you will compile and execute the following c code?

1.

#define x 5+2 2. void main(){

a. int i; b. i=x*x*x;

c.

printf("%d",i);3. }

[1 mark]

a. 343

b. 27c. 133

d. Compiler

ix. User-defined data types can be derived using___________.

a. struct

b. enum

c.

typedefd. All of the mentioned

[1 mark]

x. Which of the following is a unary operator?

a. && c. ? :

b. ! d. %c[1 mark]

xi. What is the output of this C code?

1.

#include

2.

int main()3.

{4. foo();5. foo();6. }7.

8.

void foo()9.

{10.

int i = 11;11.

printf("%d ", i);12. static int j = 12;13. j = j + 1;14. printf("%d\n", j);15. }

a. 11 12 11 12

b. 11 13 11 14

c. 11 12 11 13

d. Compile time error

[1 mark]

xii. Which of these statements relates to modularization?

a.

Application code is subdivided into separate subprograms, with each running aspecific function or subroutine.


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b. Parts of code can be split up and worked on by multiple programmers, teams or

by an individual over time, with each part of code dedicated to doing on specific

task.c. Subprograms are recyclable, and the programmer can simply call on an existing

module in a new program that he/she is working on, saving time and energy in

his/her work.

d.

All of the above [1 mark]

xiii. What will be the output of the program below?

#include

int main(){

int k=1;printf("%d = = 1 is %s\n", k, k= =1?"TRUE":"FALSE");return 0;

}

a. k = = 1 is TRUE

b. 1 = = 1 is TRUEc. 1 = = 1 is FALSE

d. K = = 1 is FALSE

[1 mark]

xiv. What does fp point to in the program below?

#include

int main(){

FILE *fp;fp=fopen("trial", "r");return 0;

}

a. The first character in the file b. A pointer to the beginning of the file.

c. The name of the file.

d. The last character in the file.[1 mark]

xv. The sequential model of software development which has no feedback is known as the:

a. Spiral Model

b. Waterfall Modelc. Fountain Model

d. Iterative Model[1 mark]

Question 3 [15 marks][7.5 marks+6.5 mark +1 mark]


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a. Examine the program shown in Figure 3 and list all of the syntax and logical errors that are

present by stating the line number, the error [1/2 mark] and indicating the correct syntax or

logic [1/2 mark]. The program is written to swap the values of num1 and num2 into the othervariable. So at the end of the program, the original value of num1 should be in num2 and the

original value of num2 will be in num1.

Mark and correct each highlighted issue to a max of 5 marks. There are 10 opportunities formarks.

[5 marks]1. #include ;2.3. void swap(a, b);4. {5. temp = a;6. a = b;7. b = temp;8. return();9. }10.

11. int main();12. {13. num1 = 10, num2 = 20;14.15. printf("Before swapping num1 = %d num2 = %d\n", num1, num2);16. swap(int num1, int num2);17.18. printf("After swapping num1 = %d num2 = %d \n", num1, num2);19. return();20. }

Figure 3

b. Explain the scope of the variables num1 and temp.

[2 marks]Answer:

They have local scope[1 mark]. A variable that is declared inside a function definition is local. It

is created and destroyed every time the function is executed, and it cannot be accessed by anycode outside the function. [1 mark]

c. Using the code example briefly explain term call-by-value.

[1 mark]

The values of num1 and num2 are copied and passed to a and b. The value of num1 and

num2 do not change.

b. Write the C-program for a time converter that will request and accept the time in Bridgetown

and ask the user for a number representing a second city. The options for the second country

are 1- New York, 2- London (England), 3- Toronto, 4- Hong Kong, 5- Acapulco (Mexico), 6-Detroit, and 7- St. George's (Grenada). You must use a switch statement to print the time in

Barbados and the time in the given city during the summer months. The summer time

conversion is as follows:

1- New York: Same as Bridgetown

2- London (England): +4 hours

3- Toronto: Same as Bridgetown

4-

Hong Kong: +12 hours


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5- Acapulco: -2 hours

If any other city is given as input the program should print a suitable message.[7 marks]

#include

main( ){int city;int hours, minutes; // 1 mark for variables used in program char mode[3];

// 1 mark for prompting and scanning variables correctlyprintf(“Please enter the time in Barbados in the format 12:00”); scanf(“%d:%d”, &hours, &minutes);

printf(“Is it AM or PM?”); // 1 mark for some accommodation for AM/PM scanf(“%s”, mode);

// 1 mark to request and readprintf(“Please enter the number indicating the second city”);

printf(“ 1- New York, 2- London (England), 3- Toronto, 4- Hong Kong”); printf(“ 5- Acapulco (Mexico)”);

scanf(“%d”, &city);

switch( city ){ // No change and a reasonable default 1 mark// hours+4 , +12, –2 1 mark

case 1:case 3: printf(“No change in time”);case 2: hours += 4;case 4: hours += 12;case 5: hours -= 2;

default : printf(“ERROR: Your second city is not known”); }// 1 mark for accommodating for 12 hrs or 24 hrs (if military time used)

if ((hours > 12) && (strcmp(mode, “AM”)) {hours = 12 – hours;strcpy(“PM”, mode);}

else if ((hours > 12) && (strcmp(mode, “PM”)) {hours = 12 – hours;strcpy(“AM”, mode);}

else if ((hours < 0) && (strcmp(mode, “PM”)) {hours = 12 + hours;strcpy(“AM”, mode);}

else if ((hours > 12) && (strcmp(mode, “AM”)) {hours = 12 + hours;strcpy(“PM”, mode);}

printf(“Second city time is %d:%d %s”, hours, minutes, mode);

} // end program

Question 4 [15 marks][7 marks+4 marks+4marks]

a. Write a function called swapI t that accepts two character arrays (string1 and string2 are arrays

filled with characters and string2 is the same size as string1), an integer value for the size of the

arrays (arraysize), and swaps the contents of the strings i.e. contents of two strings areinterchanged.

For example, if the declarations and initializations are as follows

char string1 [] = “School”;


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andchar string2 [] = “Pastel”;

thenstring2 will become “School”

andstring1 will become “Pastel”

[5 marks]void swapit(char string1[], charstring2[], int arraysize) // 1 mark

{ const int mysize = arraysize; // 1 mark declarations

char temparray [mysize];

for (int i = 0; i < arraysize; i++) // 1 mark loop to temporarily store

temparray [i] = string1[i];

for (i = 0; i < arraysize; i++) // 1 mark loop 2 to copy one to another

string1 [i] = string2[i];

for (i = 0; i < arraysize; i++) // 1 mark loop 3 copy out of temporary storage

string2 [i] = temparray[i];

return;}

b. A certain computer stores floating point numbers using a 10-bit mantissa, a 5-bit exponent (in

excess 2n-1

notation) and 1 bit for the sign. Show how the number 20.375 would be stored in a16-bit word. (Assume the exponent is represented in Sign and Magnitude form). What is the

error in the representation?

[5 marks]0 1 0 1 0 0 0 1 1 0 0 1 0 1 0 1

sign mantissa exponent

Sign bit [ 1 mark]

Convert whole part to binary [1/2 mark] Convert fraction to binary [1/2 mark]

Result: 10100.01100

Exponent is 5 [1 mark] In excess 2

n-1 notation with 5 bits => 5 + 2

5-1[1 mark]

Convert to binary 10101 [1 mark]

c. The basic outline of a C program is shown below:#include int main(){ FILE *fpt1, *fpt2;

int num_t;int num_line;

if ((fpt1 = fopen(“mockingbird.txt”, “r”) == NULL) ||(fpt2 = fopen(“counter.txt”, “r”) == NULL))

{ printf(“Can’t open the files\!\n”); exit(1);

}//...


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//Point A//(i)num_t = 0; //[1/2 mark]num_line = 0; //[1/2 mark] while (!feof(fpt1)) //[1/2 mark]{ fscanf( fpt1, “%c%”, &mychar); //[1/2 mark]

if (mychar == „t‟) //[1/2 mark]

num_t++; //[1/2 mark]//[1/2 mark]if ((mychar == „.‟)||(mychar == „!‟)|| (mychar == „?‟))

num_line++; //[1/2 mark]}

//(ii)fprintf(fptr2, “%d, %d”, num_t, num_line);//[1 mark]

//...

fclose(fpt1);

fclose(fpt2);

return 0;}

Assume that mockingbird.txt has a format similar to the following:

When he was nearly thirteen, my brother Jem got his arm badly broken atthe elbow. When it healed, and Jem's fears of never being able to playfootball were assuaged, he was seldom self-conscious about his injury.His left arm was somewhat shorter than his right; when he stood orwalked, the back of his hand was at right angles to his body, his thumbparallel to his thigh. He couldn't have cared less, so long as he could

pass and punt. When enough years had gone by to enable us to look backon them, we sometimes discussed the events leading to his accident. Imaintain that the Ewells started it all, but Jem, who was four years mysenior, said it started long before that.

Write the code that will be inserted at Point A, by declaring any additional variables thatyou need and writing code to do the following:

i. Read in the contents of mockingbird.txt character by character and count allof the occurrences of the letter „t‟ and the number of sentences in the file.

Remember that sentences end with full-stops, question marks and exclamation

marks.[4 marks]

ii. Output the number of the occurrences of the letter „t‟ and the number of

sentences in the story to the file counter.txt. [1 mark]

END OF EXAM

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Computer Science 2015