Basic concepts on Pointers & Pointer to pointer

What will be the output of the following C code?
#include <stdio.h>
int main()
{
char *p = NULL;
char *q = 0;
if (p)
printf(" p ");
else
printf("nullp");
if (q)
printf("q\n");
else
printf(" nullq\n");
}
1. nullp nullq
2. Depends on the compiler
3. x nullq where x can be p or nullp depending on the value of NULL
4. p q
What will be the output of the following C code?

#include <stdio.h>
int main()
{
int i = 10;
void *p = &i;
printf("%d\n", (int)*p);
return 0;
}
1. Compile time error
2. Segmentation fault/runtime crash
3. 10
4. Undefined behaviour
What will be the output of the following C code?

#include <stdio.h>
int main()
{
int i = 10;
void *p = &i;
printf("%f\n", *(float*)p);
return 0;
}
1. Compile time error
2. Undefined behaviour
3. 10
4. 0.000000
What will be the output of the following C code?
#include <stdio.h>
int *f();
int main()
{
int *p = f();
printf("%d\n", *p);
}
int *f()
{
int *j = (int*)malloc(sizeof(int));
*j = 10;
return j;
}
1. 10
2. Compile time error
3. Segmentation fault/runtime crash since pointer to local variable is returned
4. Undefined behaviour
What will be the output of the following C code?

#include <stdio.h>
int *f();
int main()
{
int *p = f();
printf("%d\n", *p);
}
int *f()
{
int j = 10;
return &j;
}
1. 10
2. Compile time error
3. Segmentation fault/runtime crash
4. Undefined behaviour
Comment on the following pointer declaration.

int *ptr, p;
1. ptr is a pointer to integer, p is not
2. ptr and p, both are pointers to integer
3. ptr is a pointer to integer, p may or may not be
4. ptr and p both are not pointers to integer
What will be the output of the following C code?

#include <stdio.h>
int main()
{
int *ptr, a = 10;
ptr = &a;
*ptr += 1;
printf("%d,%d/n", *ptr, a);
}
1. 10,10
2. 10,11
3. 11,10
4. 11,11
Comment on the following C statement.

const int *ptr;
1. You cannot change the value pointed by ptr
2. You cannot change the pointer ptr itself
3. You May or may not change the value pointed by ptr
4. You can change the pointer as well as the value pointed by it
Which is an indirection operator among the following?
1. &
2. *
3. ->
4. .
Which of the following does not initialize ptr to null (assuming variable declaration of a as int a=0;)?
1. int *ptr = &a;
2. int *ptr = &a – &a;
3. int *ptr = a – a;
4. All of the mentioned
What will be the output of the following C code?

#include <stdio.h>
int x = 0;
void main()
{
int *ptr = &x;
printf("%p\n", ptr);
x++;
printf("%p\n ", ptr);
}
1. Same address
2. Different address
3. Compile time error
4. Varies
What will be the output of the following C code?

#include <stdio.h>
int x = 0;
void main()
{
int *const ptr = &x;
printf("%p\n", ptr);
ptr++;
printf("%p\n ", ptr);
}
1. 0 1
2. Compile time error
3. 0xbfd605e8 0xbfd605ec
4. 0xbfd605e8 0xbfd605e8
What will be the output of the following C code?

#include <stdio.h>
void main()
{
int x = 0;
int *ptr = &x;
printf("%p\n", ptr);
ptr++;
printf("%p\n ", ptr);
}
1. 0xbfd605e8 0xbfd605ec
2. 0xbfd605e8 0cbfd60520
3. 0xbfd605e8 0xbfd605e9
4. Run time error
What will be the output of the following C code?

#include <stdio.h>
void main()
{
int x = 0;
int *ptr = &5;
printf("%p\n", ptr);
}
1. 5
2. Address of 5
3. Nothing
4. Compile time error
What will be the output of the following C code?
#include <stdio.h>
void main()
{
int x = 0;
int *ptr = &x;
printf("%d\n", *ptr);
}
1. Address of x
2. Junk value
3. 0
4. Run time error
What will be the output of the following C code?
#include <stdio.h>
void main()
{
int k = 5;
int *p = &k;
int **m = &p;
printf("%d%d%d\n", k, *p, **m);
}
1. 5 5 5
2. 5 5 junk value
3. 5 junk junk
4. Run time error
What will be the output of the following C code?

#include <stdio.h>
void main()
{
int k = 5;
int *p = &k;
int **m = &p;
**m = 6;
printf("%d\n", k);
}
1. 5
2. Compile time error
3. 6
4. junk
What will be the output of the following C code?
#include <stdio.h>
void main()
{
int a[3] = {1, 2, 3};
int *p = a;
int *r = &p;
printf("%d", (**r));
}
1. 1
2. Compile time error
3. Address of a
4. Junk value
What will be the output of the following C code?

#include <stdio.h>
void main()
{
int a[3] = {1, 2, 3};
int *p = a;
int **r = &p;
printf("%p %p", *r, a);
}
1. Different address is printed
2. 1 2
3. Same address is printed
4. 1 1
How many number of pointer (*) does C have against a pointer variable declaration?
1. 7
2. 127
3. 255
4. No limits
What will be the output of the following C code?

#include <stdio.h>
int main()
{
int a = 1, b = 2, c = 3;
int *ptr1 = &a, *ptr2 = &b, *ptr3 = &c;
int **sptr = &ptr1; //-Ref
*sptr = ptr2;
}
1. ptr1 points to a
2. ptr1 points to b
3. sptr points to ptr2
4. none of the mentioned
What will be the output of the following C code?

#include <stdio.h>
void main()
{
int a[3] = {1, 2, 3};
int *p = a;
int **r = &p;
printf("%p %p", *r, a);
}
1. Different address is printed
2. 1 2
3. Same address is printed
4. 1 1
What substitution should be made to //-Ref such that ptr1 points to variable c in the following C code?
#include <stdio.h>
int main()
{
int a = 1, b = 2, c = 3;
int *ptr1 = &a;
int **sptr = &ptr1;
//-Ref
}
1. *sptr = &c;
2. **sptr = &c;
3. *ptr1 = &c;
4. none of the mentioned
Which of the following declaration will result in run-time error?
1. int **c = &c;
2. int **c = &*c;
3. int **c = **c;
4. none of the mentioned
Comment on the output of the following C code.
#include <stdio.h>
int main()
{
int a = 10;
int **c -= &&a;
}
1. You cannot apply any arithmetic operand to a pointer
2. We don’t have address of an address operator
3. We have address of an address operator
4. None of the mentioned
What will be the output of the following C code?

#include <stdio.h>
void main()
{
int k = 5;
int *p = &k;
int **m = &p;
printf("%d%d%d\n", k, *p, **m);
}
1. 5 5 5
2. 5 Junk Value
3. 5 junk junk
4. Compile time error

Basic concepts on Pointers & Pointer to pointer

Quiz