Solution to E Balaguruswamy Chapter - Pointers

                                                               Solution to E Balaguruswamy

                                                                     Chapter  - Pointers

Ans 11.4 Pointer is initialized by keyword NULL or  0  in the following fashion

int  * p = NULL  , * m = 0 ;

 Ans 11.5  Following is the effect of the following statements

i.                     int a, *b = &a;  //Error Pointer being initialized with the address of an uninitialized variable

ii.                   int p ,   *p ;      //Error Multiple Declaration of p

iii.                  char *s;          

iv.                 a = (float * ) &x);

v.                   double  ( *f )( ) ;       //It declares the pointer to a function

Ans 11. 6   int M ,  n ;

    int *P1  , *P2 ;

The following are the errors in the expression given below:

i)                    P1 = &m ; //Error Pointer cannot be initialized with an uninitialized variable

ii)                   P2 = n ; // Error Pointer can only be initialized with the address of the variable

iii)                 P2 = &*&m; // Correct as the first dereferencing operator Is over powered by the second & operator

iv)                  M = P2 – P1 //Correct Pointer Subtraction Is allowed

v)                  P1 = &P2 //Error A simple pointer cannot be initialized with memory address of an another pointer, only a pointer to a pointer can be initialized in this way

  Ans11.7 Difference between the notations  *m[5] and (*m)[3]. Since * has lower precedence than  [] , *m[5] declares m  as an array of 5 pointers while (*m)[3] declares m as a pointer to an array of five elements.

Ans 11.9   int x = 10 ,  y  = 10 ;

                    int  *p1 = &x , *p2 = &y;

                The following Expression generate the following output:

i)                    (*p1)++   Output – 10

ii)                   - - (*p2)   Output  -  9

iii)                 *p1 + (*p2)--   Output  - 20

iv)                   ++(*p2) - *p1  Output  -  1

Ans 11.12  Following Output is  generated by the following code :

                int m = 100 ;

                int *p1 = &m;

                int **p2 = &p1;

                printf(“%d” , **p2);

                Output :

                100

Ans 11. 13   Following is the error in the given code

                                int **p1 , * p2 ;

                                p2 = &p1  // It should be  p1 =&p2

Explanation: p1 is a pointer to a pointer so it should always point a pointer

Ans11.14  Difference between the two expression name + 10; and *(name + 10 ) is that the first expression refers to all the characters after the 10^th position in the array name or rather simply we  can say that it will the array name from the 10^th character whereas the second expression refers specifically to the 10^th character of the array of name .

Ans 11.15  Following is the output of the code given below

                                int m[2] ;

                                *(m+1)

                                *m = *(m + 1);

                                printf(“ %d “ , m[0] );

Output:

                                100

Ans 11.16    int m[2];

                       int *p = m ;

                       m[0] = 100;

                       m[1] = 200;

                       printf(“%d %d “ , ++*p , *p );

                      Output:

                      101  100

Ans 11.17    Output of the following code :

                 int f(char *p );

                main()

                {              char str[] = “ANSI”;

                                printf(“%d” , f(str) );

                }

                int f(char *p )

                {              char *q = p ;

                                while (*++p ) ;

                                return (p – q );                  }

Output :

4

Ans 11.18  Following declarations are not the same:

                1 . void search ( int *m[] , int x) { }

                In this the parameter in the definition is a integer pointer array.

                2. void search ( int **m  ,int x ) {}

                In this the parameter in the definition is a integer pointer to a pointer.

Ans 11.19   Following declaration is are same

                char *s;

                char s[5] ;

                As name of the array is a pointer to the first element of the array it’s as same as declaring a pointers which when incremented can be used to store a list of values same as an array.

Ans 11.20  The following is the correct way to declare a pointer to a function.

                int (*p)(void);