POINTERS

A pointer is

• A keyword used to create variables

      

• A variable that stores address of an instruction

• A variable that stores address of other variable

• All of the above

Comment on the following pointer declaration?

    int *ptr, p;

• ptr is a pointer to integer, p is not

      

• ptr and p,both are pointers to integer

• ptr is pointer to integer,p may or may not be

• ptr and p both are not pointers to integers

What will be the output of the following C code?

#include <stdio.h>

    void m(int *p)

    {

        int i = 0;

        for(i = 0;i < 5; i++)

        printf("%d\t", p[i]);

    }

    void main()

    {

        int a[5] = {6, 5, 3};

        m(&a);

    }

• 0 0 0 0 0

• 6 5 3 0 0

• Run time error

• 6 5 3 junk junk

Can you combine the following two statements into one?

1.     char *p;

2.     p = (char*) malloc(100);

• char p = *malloc(100);

• char *p = (char) malloc(100);

• char *p = (char*)malloc(100);

• char p = (char )(malloc*)(100);

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);

    }

• 5 5 5

• 5 5 junkvalue

• 5 junk junk

• Run time error

What will be the output of the  following code snippet.

#include <stdio.h>

void main()

{

char *p=NULL;

char *q=0;

if(p)

printf(" p ");

else

printf("nullp");

if(q)

printf(" q ");

else

printf(" nullq");

}

• p,q

   

• Depends on the compiler

• x nullq where x can be p or nullp depending on the value of NULL

• nullp nullq

Point out the compile time error in the program given below.

#include<stdio.h>

int main()

{

    int *x;

    *x=100;

    return 0;

}

• Error: invalid assignment for x

   

• Error: suspicious pointer conversion

• No error

• None of the above

What will be the output of the program ?

#include<stdio.h>

 

int main()

{

    int x=30, *y, *z;

    y=&x; /* Assume address of x is 500 and integer is 4 byte size */

    z=y;

   *y++ = *z++;

    x++;

    printf("x=%d, y=%d, z=%d\n", x, y, z);

    return 0;

}

• x=31, y=502, z=502

• x=31, y=500, z=500

• x=31, y=498, z=498

• x=31, y=504, z=504

What will be the output of the following C code?

void main() {   int a[] = {1,2,3,4,5}, *p;   p = a;   ++*p;   printf("%d ", *p);   p += 2;   printf("%d ", *p); }

• 24

• 34

• 22

• 23

 What is the output of this program?

#include <stdio.h> void test(int *, int *); void main() { int a = 5 , b = 6; test(&a,&b); printf("%d %d",a,b); } void test(int *p, int *q) { *p = *p * *q; *q = *p / *q; *p = *p / *q; }

• 30 5

• 6 5

• 5 6

• None of the above