C Advanced Pointer

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Question 1

‘ptrdata’ is a pointer to a data type. The expression *ptrdata++ is evaluated as (in C++) :
 

  • Depends on compiler
     

  • (*ptrdata)++
     

  • *(ptrdata)++
     

  • *(ptrdata++)
     

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Question 2

What is printed by the following C program?

C 
$include <stdio.h>
int f(int x, int *py, int **ppz)
{
  int y, z;
  **ppz += 1; 
   z  = **ppz;
  *py += 2;
   y = *py;
   x += 3;
   return x + y + z;
}
 
void main()
{
   int c, *b, **a;
   c = 4;
   b = &c;
   a = &b; 
   printf( "%d", f(c,b,a));
   getchar();
}

  • 18

  • 19

  • 21

  • 22

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Question 3

What will be output of the following program? Assume that you are running this program in little-endian processor.

C 
#include<stdio.h>

int main() {
    short a = 320;
    char * ptr;
    ptr = (char * ) & a;
    printf("%d", * ptr);
    return 0;
}

  • 1

  • 320

  • 64

  • Compilation error

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Question 4

Consider the following C function

C 
#include <stdio.h>
int main(void)
   {
    char c[ ] = "ICRBCSIT17";
    char *p=c;
    printf("%s", c+2[p] – 6[p] – 1);
    return 0;
   }

The output of the program is

  • SI

  • IT

  • TI

  • 17

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Question 5

Find out the correct statement for the following program. C 
#include "stdio.h"

typedef int (*funPtr)(int);

int inc(int a)
{
 printf("Inside inc() %d\\n",a);
 return (a+1);
}

int main()
{

 funPtr incPtr1 = NULL, incPtr2 = NULL;

 incPtr1 = &inc; /* (1) */
 incPtr2 = inc; /* (2) */

 (*incPtr1)(5); /* (3) */
 incPtr2(5); /* (4)*/

 return 0;
}
  • Line with comment (1) will give compile error.
  • Line with comment (2) will give compile error.
  • Lines with (1) & (3) will give compile error.
  • Lines with (2) & (4) will give compile error.
  • No compile error and program will run without any issue.
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Question 6

In the context of the below program snippet, pick the best answer.

C 
#include <stdio.h>
int arr[10][10][10];
int main()
{
 arr[5][5][5] = 123;
 return 0;
}

Which of the given printf statement(s) would be able to print arr[5][5][5]

C 
(i) printf("%d",arr[5][5][5]);
(ii) printf("%d",*(*(*(arr+5)+5)+5));
(iii) printf("%d",(*(*(arr+5)+5))[5]);
(iv) printf("%d",*((*(arr+5))[5]+5));

  • only (i) would compile and print 123.

  • both (i) and (ii) would compile and both would print 123.

  • only (i), (ii) and (iii) would compile but only (i) and (ii) would print 123.

  • only (i), (ii) and (iii) would compile and all three would print 123.

  • all (i), (ii), (iii) and (iv) would compile but only (i) and (ii) would print 123.

  • all (i), (ii), (iii) and (iv) would compile and all would print 123.

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Question 7

C 
#include <stdio.h> 
int main()
{
 void *pVoid;
 pVoid = (void*)0;
 printf("%lu",sizeof(pVoid));
 return 0;
}

Pick the best statement for the above C program snippet.

  • Assigning (void *)0 to pVoid isn’t correct because memory hasn’t been allocated. That’s why no compile error but it'll result in run time error.

  • Assigning (void *)0 to pVoid isn’t correct because a hard coded value (here zero i.e. 0) can’t assigned to any pointer. That’s why it'll result in compile error.

  • No compile issue and no run time issue. And the size of the void pointer i.e. pVoid would equal to size of int.

  • sizeof() operator isn’t defined for a pointer of void type.

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Question 8

C 
#include <stdlib.h>
int main()
{
 int *pInt;
 int **ppInt1;
 int **ppInt2;

 pInt = (int*)malloc(sizeof(int));
 ppInt1 = (int**)malloc(10*sizeof(int*));
 ppInt2 = (int**)malloc(10*sizeof(int*));

 free(pInt);
 free(ppInt1);
 free(*ppInt2);
 return 0;
}

Choose the correct statement w.r.t. above C program.

  • malloc() for ppInt1 and ppInt2 isn’t correct. It’ll give compile time error.

  • free(*ppInt2) is not correct. It’ll give compile time error.

  • free(*ppInt2) is not correct. It’ll give run time error.

  • No issue with any of the malloc() and free() i.e. no compile/run time error.

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Question 9

Consider the following C program.

C 
# include 
int main( )
{
  static int a[] = {10, 20, 30, 40, 50};
  static int *p[] = {a, a+3, a+4, a+1, a+2};
  int **ptr = p;
  ptr++;
  printf("%d%d", ptr - p, **ptr};
}

The output of the program is _________

  • 140

  • 120

  • 100

  • 40

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Question 10

What is the output of the following C code? Assume that the address of x is 2000 (in decimal) and an integer requires four bytes of memory.

C 
#include <stdio.h>
int main()
{ 
   unsigned int x[4][3] = {{1, 2, 3}, {4, 5, 6}, 
                           {7, 8, 9}, {10, 11, 12}};
   printf("%u, %u, %u", x+3, *(x+3), *(x+2)+3);
}

  • 2036, 2036, 2036

  • 2012, 4, 2204

  • 2036, 10, 10

  • 2012, 4, 6

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