Pencil-and-Paper Assignment 5
Assigned Monday, February 11, 2002
Due Monday, February 18, 2002 (At the beginning of class)

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Solutions
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1. Given the following declaration,
   int a[] = {1,2,3,4,5};
   what are the values of the expressions below?
   (a) a - &a[3] = -3
   (b) *(a+4) = 5
   (c) *(a+5) - accesses the address beyond the end of the array - indeterminate

2. Explain the meaning of each of the following declarations:
   (a) char a[]; // creates a char[] named a, allocates no space
   (b) char *b;  // creates a char * named b, allocates no space
   (c) char c[5] = ""; // creates a char[] named c, allocates 5 spaces plus one
                       // for the null character, initializes it to an empty string
   (d) int d[] = {0,1,2}; // creates an int[] named d, reserves 3 spaces and
                          // initializes the 3 values
   (e) int *e = d+1;      // creates a pointer to an integer named d and
                          // initializes it to point to the second element in array d
   (f) char *g[];         // Creates an array of character pointers named g, no
                          // space is allocated
   (g) char *g[] = {a,b,c}; // Creates an array of character pointers named g,
                            // allocates space for 3 pointers and initializes them
                            // to the addresses stored in a, b and c
   (h) char **a;            // creates a pointer to a pointer to a char, named a
   (i) char **a = &b;       // creates a pointer to a pointer to a char named a
                            // and assigns to it the address of variable b - b
                            // should be a char *
   (j) typedef int (* C_FN)(char *, const char *); // defines C_FN as a type that
                            // is a pointer to a function that takes a char * and
                            // a const char * as parameters and returns an int

3. Given that k is an integer array starting at location 2000, 
   kPtr is a pointer to k, and each integer is stored in 4 bytes of memory: 
   (a) If the location is 0x2000, then kptr+5 points to 20 positions pas 0x2000,
       which is 0x2014 
   The second element of k is:
   (b) k[1]
   (c) *(k+1)
   (d) kptr[1]
   (e) *(kptr+1)
   (e) pointer/offset notation
  
4. Consider the following function:

   void func( char * string1, const char * string2 )
   {
        int stringsize = sizeof( string1 )/sizeof( char );
        *( string1 + stringsize -1 ) = ‘\0’;
        string1 = string1 + stringsize - 2;
        for ( ; *string2 != '\0'; string1--, string2++ )
        *string1 = *string2;
   }
   sizeof(string1) is usually 4 (4 bytes for a pointer), sizeof(char) is usually 1,
   so, despite what we might think, stringsize is 4, not the number of characters 
   in the array.
   The next line puts a null terminator after the 3rd byte in string1
   The last two lines copy 3 characters from string2 into string1 in
   reverse order - but it doesn't work because it doesn't stop when it reaches the
   beginning of string1
 
5. Provide the definition for each of the following structures.
   (a) A structure called Address that contains character arrays
       streetAddress[ 25 ], city[ 20 ], state[ 3 ] and zipCode[ 6 ].
       struct Address {
           char streetAddress[25];
           char city[20];
           char state[3];
           char zipCode[6];
       };
   (b) Structure Student that contains arrays firstName[ 15 ] and
       lastName[ 15 ], integer id, floating-point GPA, and 
       variable homeAddress of type struct Address from part (a).
       struct Student {
           char firstName[15];
           char lastName[15];
           integer id;
           float GPA
           Address homeAddress;
       }

6. Say that you have the following in your program:
   int i;
   int *ip;
   int **ipp;
   i = 4000;
   ip = &i;
   ipp = &ip;
   Say that i is stored at memory location 0x606EF0, ip is stored at
   memory location 0x606EF8 and ipp is stored at memory location 0x606F08.
   a)  Draw a map of the memory and fill in the values of each variable.
       variable:   location:    contents:
       i:          0x606EF0         4000
       ip:         0x606EF8     0x606EF0
       ipp:        0x606F08     0x606EF8
   b)  What is the value of each of the following (some are not even
       logically valid expressions - note which ones are not):
       i = 4000, &i = 0x606EF0, *i not valid, &ip = 0x606EF8
       ip = 0x606EF0, *ip = 4000, **ip not valid, &*ipp=0x606EF8
      *ipp = 0x606EF0, **ipp = 4000, &&i not valid, &ipp = 0x606F08. 

7. Do problem 6.12 in Deitel and Deitel
class Rectangle {
public:
	Rectangle(float =1, float=1);
	float perimeter();
	float area();
	void set_width(float);
	void set_length(float);
	float get_width();
	float get_length();
private:
	float width;
	float length;
};

Rectangle::Rectangle(float w, float l)
{
	set_width(w);
	set_length(l);
}

float Rectangle::perimeter()
{
	return (2*width + 2*length);
}

float Rectangle::area()
{
	return length*width;
}

void Rectangle::set_width(float w)
{
	if (w>0 && w < 20) width = w;
	else width = 1;
}

void Rectangle::set_length(float l)
{
	if (l>0 && l < 20) length = l;
	else length = 1;
}

float Rectangle::get_width()
{
    return width;
}

float Rectangle::get_length()
{
	return length;
}

8. Do problem 16.7 in Deitel and Deitel
   a) customerRecord.lastName
   b) customerPtr->lastNmae
   c) customerRecord.firstName
   d) customerPtr->firstName
   e) customerRecord.customerNumber;
   f) customerPtr->customerNumber;
   g) customerRecord.personal.phoneNumber
   h) customerPtr->personal.phoneNumber
   i) customerRecord.personal.address
   j) customerPtr->personal.address
   k) customerRecord.personal.city
   l) customerPtr->personal.city
   m) customerRecord.personal.state
   n) customerPtr->personal.state
   o) customerRecord.personal.zipcode
   p) customerPtr->personal.zipcode