Department of Computer Science & Engineering 
                                                 Indian Institute of Technology Kharagpur 
                                                                              
                                                                              
                                                                Practice Sheet #03 
           
          Topic: C-Programming Constructs                                                                           Date: 17-01-2017 
           
                        1.    Consider the following C function. 
                              float f(float x, int y) 
                              { 
                                float p, s; int i; 
                                for (s=1, p=1, i=1; i < y; i ++) 
                                { 
                                  p*= x/i; 
                                  s+=p; 
                                } 
                                return s; 
                              }   
                              For large values of y, the return value of the function f best approximates 
                                   (a)   x^y  
                                   (b)   e^x  
                                   (c)   ln(1 + x) 
                                   (d)   x^x 
                                          
                        2.    Consider the following program fragment for reversing the digits in a given integer to obtain a 
                              new integer. Let n = D1D2…Dm 
                              int n, rev; 
                              rev = 0; 
                              while (n > 0) 
                              { 
                                 rev = rev*10 + n%10; 
                                 n = n/10; 
                              } 
                               
                              The loop invariant condition at the end of the ith iteration is: 
                                   (a)   n = D1D2….Dm-i and rev = DmDm-1…Dm-i+1  
                                   (b)   n = Dm-i+1…Dm-1Dm and rev = Dm-1….D2D1  
                                   (c)   n != rev 
                                   (d)  n = D1D2….Dm and rev = DmDm-1…D2D1 
                               
                        3.    Consider the following C program 
                              main() 
                              { 
                                  int x, y, m, n; 
                                  scanf ("%d %d", &x, &y); 
                                  /* Assume x > 0 and y > 0  */ 
                                  m = x; 
                                  n = y; 
                                  while (m! = n) 
                                  { 
                                      if (m > n) 
                                          m = m - n; 
                                      else 
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                                            n = n - m; 
                                    } 
                                    print f ("% d", n); 
                                } 
                                 
                                The program computes: 
                                     (a)    x ÷ y using repeated subtraction 
                                     (b)    x mod y using repeated subtraction 
                                     (c)     the greatest common divisor of x and y 
                                     (d)    the least common multiple of x and y
                                 
                         4.     What does the following algorithm approximate? 
                                x = m; 
                                y = 1; 
                                while (x - y > e) 
                                { 
                                    x = (x + y)/2; 
                                    y = m/m; 
                                } 
                                print(x); 
                                 
                                (Assume m > 1, e > 0). 
                                     (a)    Log m 
                                     (b)   m2 
                                     (c)    m1/2   
                                     (d)    m1/3 
                                 
                         5.     Consider the following C-program: 
                                void foo(int n, int sum) 
                                { 
                                  int k = 0, j = 0; 
                                  if (n == 0) return; 
                                    k = n % 10;  
                                  j = n / 10; 
                                  sum = sum + k; 
                                  foo (j, sum); 
                                  printf ("%d,", k); 
                                } 
                                   
                                int main () 
                                { 
                                  int a = 2048, sum = 0; 
                                  foo (a, sum); 
                                  printf ("%d\n", sum); 
                                     
                                  getchar(); 
                                } 
                                 
                                What does the above program print? 
                                     (a)    8, 4, 0, 2, 14 
                                     (b)   8, 4, 0, 2, 0 
                                     (c)    2, 0, 4, 8, 14   
                                     (d)    2, 0, 4, 8, 0 
                                 
                         6.     Consider line number 3 of the following C- program. 
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                             int main ( ) {                   /* Line 1 */ 
                               int I, N;                      /* Line 2 */ 
                               fro (I = 0, I < N, I++);       /* Line 3 */ 
                             } 
                              
                             Identify the compiler's response about this line while creating the object-module 
                                  (a)    No compilation error 
                                  (b)   Only a lexical error  
                                   (c)     Only syntactic errors 
                                   (d)    Both lexical and syntactic errors 
                              
                       7.    Consider the following code fragment: 
                               if (fork() == 0) 
                               { a = a + 5; printf(“%d,%d\n”, a, &a); } 
                               else { a = a –5; printf(“%d, %d\n”, a, &a); }  
                             Let u, v be the values printed by the parent process, and x, y be the values printed by the child 
                             process. Which one of the following is TRUE? 
                                  (a)    u = x + 10 and v = y 
                                  (b)   u = x + 10 and v != y  
                                  (c)   u + 10 = x and v = y   
                                   (b)    u + 10 = x and v != y 
                              
                       8.    Consider the following C code segment. 
                             for (i = 0, i 
                             int main( ) 
                             { 
                                int i, j, k = 0; 
                                j = 2 * 3 / 4 + 2.0 / 5 + 8 / 5; 
                                k  -= --j; 
                                for (i = 0; i < 5; i++) 
                                { 
                                   switch(i + k) 
                                   { 
                                      case 1: 
                                      case 2: printf("\n%d", i + k); 
                                      case 3: printf("\n%d", i + k); 
                                      default: printf("\n%d", i + k); 
                                   } 
                                } 
                                return 0; 
                             } 
                              
                              
                             The number of times printf statement is executed is __________. 
                                  (a)    8 
                                  (b)    9 
                                  (c)    10 
                                  (d)    11 
                              
                       11.  Determine what the following program prints. (10) 
                             #include  
                             main () 
                             int r, t, m; 
                             scanf("%d", &r); /* Enter the last four digits of your roll number as r */ 
                             printf("r = %d\n", r); 
                             m = 0; 
                             while (r > 0){ 
                             t = r % 10; 
                             if (t > m) m = t; 
                             r = r / 10; 
                             printf("m = %d\n", m); 
                             } 
                              
                       12.  How many times is the body of the following loop executed? 
                             int i; 
                             for (i=0; i<100; i=i+3) printf("i = %d\n", i); 
                                  (a)    100 
                                  (b)   97 
                                  (c)    34  
                                  (d)    33 
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