ITEC114 Structured Programming Midterm Exam, Spring 2015/ April Instructor: Akile Oday Research Assistant: Mohammed Abubakar SOLUTIONS

Transcription

1 ITEC114 Structured Programming Midterm Exam, Spring 2015/ April 2016 Instructor: Akile Oday Research Assistant: Mohammed Abubakar SOLUTIONS Student Name: Student Number: Question Points Score Q1 Q Q12 24 Q13 20 Q14 30 Total Duration of the exam is 75 minutes Ask if any question in first 30 minutes You are not allowed to leave the class within first 30 minutes

2 (2.5 p.) Q 1 - What is the output of the below code snippet? for()printf("hello"); A - Infinite loop B - Prints Hello once. C - No output Answer : D Compiler error, semi colons need to appear though the expressions are optional for the for loop. (2.5 p.) Q 2 - What is the output of the following program? int i = 1; while(++i <= 5) printf("%d ",i++); A B C D , at while first incremented and later compared and in printf printed first and incremented later (2.5 p.) Q 3 - In the given below code, the function fopen() uses "r" to open the file source.txt for which purpose? void main () FILE *fp; fp = fopen("source.txt", "r"); A - For reading B - For reading and writing C - For creating a new file "source.txt" for reading D - For creating a new file "source.txt" for writing 2

3 Answer : A To open a file in C programming, we can use library function fopen(). In the given above code, fopen() function is opening a file source.txt for reading. Here, r stands for reading. If, fopen() function does not find any file for reading, returns NULL (2.5 p.) Q 4 - What is the output of the following program? int a[3] = 2,1; printf("%d", a[a[1]]); A - 0 B - 1 C - 2 D - 3 1, The inner indirection evaluates to 1, and the value at index 1 for outer indirection is 1. (2.5 p.) Q 5 - What is the output of the following program? int x = 1; do printf("%d ", x); while(x++<=1); A - 1 B C - No output 1 2, do..while is an entry control loop. As the expression x++ is post form loop continues for 2nd time also. (2.5 p.) Q 6 - What is the output of the following code snippet? 3

4 int x = 5; if(x=5) if(x=5) printf("hello"); printf("hi"); A - HelloHi B - Hi C - Hello D - Compiler error Answer : A HelloHi, both the if statement s expression evaluates to be true. (2.5 p.) Q 7 - What is the output of the following program? void main int x = 1; switch(x) default: printf("hello"); case 1: printf("hi"); break; A - Hello B - Hi C - HelloHi Hi, control reaches default-case after comparing the rest of case constants. (2.5 p.) Q 8 - What is the output of the following program? void f(int a[]) int i; for(i=0; i<3; i++) a[i]++; int i,a[] = 10, 20, 30; 4

5 f(a); for(i=0; i<3; ++i) printf("%d ",a[i]); A B C - Compile error D - Runtime error Arrays are always passed by reference. (2.5 p.) Q 9 - What is the output of the below code snippet? for(;;)printf("hello"); A - Infinite loop B - Prints Hello once. C - No output Answer : A infinite loop, with second expression of for being absent it is considered as true by default. (2.5 p.) Q 10 - What is the output of the following program? void swap(int m, int n) int x = m; m = n; n = x; int x=5, y=3; swap(x,y); printf("%d %d", x, y); 5

6 A B C (2.5 p.) Q 11 - What is the following program doing? FILE *p; p=fopen("a.txt",'r'); Answer : A A - Trying to open a.txt in read mode B - Trying to open a.txt in write mode. C - p is an invalid identifier (24 p.) Q 12- What will be the output of the program? Without trace table will not be marked. #include "stdafx.h" int f1( int x) if (x<=4) return 8; else return x-1; int f2( int x, int y) x=x+1; y=y+2; return x+y; int k=3,m=5,r=0; printf("1> %d %d \n",f1(k),f2(m,r)); r=f1(m); printf("2> %d %d \n",r,f2(r,r)); k=f1(r-2); printf("3> %d %d \n",k,r); Trace Table main() f1() f2() k m r x x y Output 1 > > > 8 4 6

7 (20 p.) Q 13 Complete the following program. The following C program creates a file called emp.txt and store information about a person, in terms of his age. Complete the following program. #include "stdafx.h" FILE ; create a file pointer int age; fptr = fopen("emp.txt", " "); opens a file for writing printf("enter the age\n"); scanf("%d", ); read age fprintf(, "Age = \n", age); prints age in emp.txt file ; close the file Soln: #include "stdafx.h" FILE *fptr; int age; fptr = fopen("emp.txt", "w"); printf("enter the age\n"); scanf("%d", &age); fprintf(fptr, "Age = %d\n", age); fclose(fptr); (30 p.) Q 14 - Write a C program with a function called getrandom() which will generate 10 random numbers and return them using an array and print them in main() as follows: 7

8 #include "stdafx.h" #include "stdlib.h" #include "time.h" int getrandom( ) int i,rnum; rnum= rand()%10; return rnum; void main () int r[10]; int i; srand(time( NULL ) ); for ( i = 0; i < 10; i++ ) r[i]=getrandom(); printf( "p[%d] : %d\n", i, r[i]); 8