EAS 230 Fall 2002 Section B

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1 EAS 230 Fall 2002 Section B Exam #2 Name: Person Number: Instructions: ƒ Total points are 100, distributed as shown by [ ]. ƒ Duration of the Exam is 50 minutes.

2 I ) State whether True or False [25] Indicate whether the following statements are True(T) or False(F)(no explanation required). 1) The & operator is used to identify call-by-reference function arguments. Ans: T 2) A function can be made to return more than one value using the return statement. Ans: F, only one value can be returned using the return statement 3) char str = EAS 230 is a valid string initialization. Ans: F, char str[] = EAS 230 is valid 4) ofstream class is used to create an input file stream object. Ans: F, ofstream is used to create an output file stream object. 5) if CSquare is declared as a class with side as a public data member. CSquare square1; //where square1 is an object of the class CSquare then the statement square1.side = 10; is valid. Ans: True, side is a public data member. 6) The header file in which the classes ifstream, ofstream and fstream are declared is stream.h. Ans: F, the header file is fstream.h 7) Bubble sort algorithm makes several passes through the unsorted array and on each pass compares and swaps(if required) successive pair of elements and thereby sorts the array. Ans: T 8) An array of characters can store integers and floating point numbers as well. Ans: F, Array of characters can store only characters. 9) Binary search algorithm can be operated on an unsorted array. Ans: F 10) An object can be passed to the function as an argument but an object cannot be returned by a function. Ans: F, return(object) is valid. 11) fopen is used to handle multiple files that use the same stream object. Ans: T 12) An array can be passed by value to a function. Ans: F, array can only be passed by reference i.e by specifying the name of the array in the function call. 13) In C++, array indexing starts from 0 by default. Ans: T

3 (II) [ 25] 1) What are call by reference and call by value functions? [3] Ans: when calling a function by value, what is passed to the function are values of the arguments in the function call but never specify variables themselves. Ampersand sign is not required in such calls.if not a void function, they can return only one value using an explicit return statement. Exactly reverse argument applies when the functions are called by reference. Majority of the times these functions are void functions and are capable of returning more than one value to the calling function *also refer to the class notes on the web. 2) What are friend functions and when are they used? [2] $QVThere can arise a situation, which might require two classes to share a particular function. In such situations, C++ allows common functions to be made friendly with both classes, thereby allowing the function to have an access to the private data of the classes. *also refer to the class notes on the web. 3) Explain what does this function do? [8] Void A(float x[], float y[], int length) for (int i = 0 ; i<length ; i++) float temp; temp = x[i]; x[i] = y[i]; y[i] = temp; Ans: This function swaps the values contained in the two arrays. It swaps the arrays on element by element basis and uses the temporary variable temp for swapping the values.

4 4) Point out and explain the errors in the program presented below? [12] #include<iostream.h> class ctraingle int base,height; public: ctraingle() base = 10; height = 3; ~ctraingle() int area(void); ; required (1) int ctraingle::area(void) return(0.5*base*height); int main() ctraingle traingle1, traingle2(2,10); parameterized constructor isn t defined.(2) triangle2.height = 4; height and base are private variables and cannot be traingle2.base = 6; referenced by an object.(3) and (4) cout<<traingle1.area(); cout<<traingle2.area(); return 0; (*there are 4 errors in the above program) Ans:

5 (III) [25] 1) The function add written below is a recursive function. [13] #include<iostream.h> int sum = 0; //global variable int add( int a) if(a<=0) return 0; else sum = a + add(a - 2); return sum; int main() int b = 9,sum1; sum1 =add(b); cout<<sum1; return 0; Which one of the following is the output of the above program? a)19 b) 25 c) 21 d) 23 e) none of these. Ans: sum1 = add(9) = 9 + add(7) = 9 +7+add(5) = add(3) = add(1) = add(0) = = 25

6 2) What is the out put of the program presented below? [12] #include<iostream.h> #include<string.h> int main() int length; char str1[] = "UNIVERSITY "; char str2[] = "AT BUFFALO"; length = strlen(str1); for( int i = 0;i<length;++i) cout<<str1[i]<< * ; cout<<endl; for( int i = 0;str1[i]!= \0 ;i = i+2) cout<<str1[i]<< ; cout<<endl; cout<<strcat( strcat(str1," "),str2 )<<endl; return 0; Ans: U*N*I*V*E*R*S*I*T*Y* * U I E S T UNIVERSITY AT BUFFALO two spaces

7 IV) Data structures [25] The office of records and registrations of a school requires that a database of students with outstanding bills be created. Write a C++ program to create a database of such students using Structures? 1) Declare a structure student which comprises of the following fields. [5] int person_num; char department[10]; float amount_due; 2) Use array of structures and read the above data for 10 students (records). [13] 3) Once the database is created, print the records. [7] For your understanding the output of the program for 2 records appears as shown below Ans: #include<iostream.h> struct student int person_num; char department[10]; float amount_due; ; PERSON NUM: 2336 DEPARTMENT: EAS AMOUNT DUE: $ PERSON NUM: 2789 DEPARTMENT: CSE AMOUNT DUE: $ PERSON NUM: 2336 DEPARTMENT: EAS AMOUNT DUE: $ PERSON NUM: 2789 DEPARTMENT: CSE AMOUNT DUE: $

8 student read_struct(void) //This function returns a structure variable of the type student. student stud1; char string[10]; cout<<"person NUM: "; cin >>stud1.person_num; cout<<"department: "; cin>>string; strcpy(stud1.department,string); cout<<"amount DUE: $ "; cin>>stud1.amount_due; return(stud1); void print_struct(student stud3) cout<<"person NUM: "<<stud3.person_num <<" DEPARTMENT: "<<stud3.department <<" AMOUNT DUE: $ "<<stud3.amount_due<<endl; int main() student stud2[10]; cout<<"enter the Person number, Department and Amount_due\n"; for (int i = 0;i<10;++i) stud2[i] = read_struct(); for(int i = 0;i<10;++i) print_struct(stud2[i]); return 0;

KendriyaVidyalayaSangathan Kolkata Region

KendriyaVidyalayaSangathan Kolkata Region Third Pre-Board Examination : 204-5 Please check that this question paper contains 7 questions. Please write down the Serial Number of the question before attempting