Questions

We have 12 months.

In every month we get 28 or more days. 

So that implies we get 28 days in each and every month.

It is used to get parent process identifier

Because there is no need address traansaction between processor and peripheral device but data bus is needed because data has to be read and write

Yes, using the realloc() function as shown below:

main()

{

        int *p;

        p = ( int *) malloc (20) ;

        t = p;

        t = (int *) realloc ( p, 40);

        if ( t == NULL )

        Printf (" Cannot reallocate, leaves previous allocated region unchanged ");

       else

       {

              if ( p ==t )

              ;  / * the array expanded at the same region */

             else

            { 

                 free ( p ); / * deallocate the original array */

                 p = t;  /* set p to newly allocated region */

             }

      }

}