Which operator is used to access data members of a structure, with a variable that is pointer to that structure ?

Take a look at following code:

(void*)0

What does it depicts ?

Which of the following header file(s) contain definition for NULL macro ?

What is the size of a pointer variable on Linux ?

How do you access value at position arr[i][j][k][l] using pointer ?

Which operator is used with pointer to access value at the address to which pointer points ?

Which of the following is correct about pointers ?

Take a look the following piece of code:

char *x;
x = (char*) malloc(10);

Which of the following piece of code is equivalent to it ?

What should be the output of following code:

#include<stdio.h>

int main()
{
    static char *s[] = {"hackersfriend", "coder", "learning", "lab"};
    char **ptr[] = {s+3, s+2, s+1, s}, ***p;
    p = ptr;
    ++p;
    printf("%s", **p+1);
    return 0;
}

What would be output of the following code:

#include<stdio.h>

int main()
{
    int x=4, *y, z;
    y = &x;
    printf("%d", x**y*x+*y+x);
    return 0;
}