Exercise 8.2 (Completed)

1. (Practice) Replace each of the following references to a subscripted variable with a pointer reference:
a. prices[5]
*(prices + 5)
b. grades[2]
*(grades + 2)
c. yield[10]
*(yield + 10)
d. dist[9]
*(dist + 9)
e. mile[0]
*mile
f. temp[20]
*(temp + 20)
g. celsius[16]
*(celsius + 16)
h. num[50] 
*(num + 50)
i. time[12]
*(time + 12)

2. (Practice) Replace each of the following pointer references with a subscript reference:

a. *(message+6)
message[6]
b. *amount 
amount[0]
c. *(yrs+10)
yrs[10]
d. *(stocks+2)
stocks[2]
e. *(rates+15)
rates[15]
f. *(codes+19)
codes[19]

3. (Practice) a. List three things the declaration statement double prices[5]; causes the
compiler to do.

Creates a pointer to an array location.
Declares that array a double-percision variable.
Every location before the array is also created.

b. If each double-precision number uses 8 bytes of storage, how much storage is set aside for
the prices array?

8 * 6 = 48
48 bytes are set aside for the prices array.

c. Draw a diagram similar to Figure 8.16 for the prices array.

prices
|&prices[0]|
|
|
V
|Address || Address||Address ||Address|| Address || Address|
prices[0] prices[1] prices[2] prices[3] prices[4]  prices[5]
  or         or        or        or        or         or
*prices*(prices +1)*(prices +2)*(prices +3)*(prices +4)*(prices +5)

d. Determine the byte offset in relation to the start of the prices array, corresponding to the
offset in the expression *(prices+3).

24 bytes(3 * 8) + 8 = 32 bytes
The offset is  32 bytes

4. (Practice) a. Write a declaration to store the string “This is a sample” in an array named
samtest. Include the declaration in a program that displays the values in samtest by using a
for loop that uses a pointer access to each element in the array.

#include <iostream>
using namespace std;

int main(){


	char samtest[17] = { "This is a sample" };

	for (int i = 0; i < 17; i++){
		std::cout << *(samtest+i) << endl;
	}
	
	system("PAUSE");
	return 0;

}

b. Modify the program written in Exercise 4a to display only array elements 10 through 15 (the
letters s, a, m, p, l, and e).

#include <iostream>
using namespace std;

int main(){


	char samtest[17] = { "This is a sample" };

	for (int i = 0; i < 17; i++){
		if (i >= 10 && i <= 15){
			std::cout << *(samtest + i) << endl;
		}
		
	}
	
	system("PAUSE");
	return 0;

}

5. (Practice) Write a declaration to store the following values in an array named rates: 12.9,
18.6, 11.4, 13.7, 9.5, 15.2, and 17.6. Include the declaration in a program that displays the values
in the array by using pointer notation.

#include <cmath>
#include <iostream>
using namespace std;

int main(){


	double rates[7] = { 12.9,18.6,11.4,13.7,9.5,15.2,17.6 };

	for (int i = 0; i < 7; i++){
		
			std::cout << *(rates + i) << endl;
		
	}
	
	system("PAUSE");
	return 0;

}

6. (Modify) a. Repeat Exercise 6a in Section 7.1, but use pointer references to access all array
elements.

#include <iostream>
using namespace std;

int main()

{
	const int NUMELS = 9;
	int i, prices[NUMELS];
	for (i = 0; i < NUMELS; i++)    // Enter the prices

	{
		cout << "Enter a price: ";
		cin >> *(prices + i);
	}

	cout << endl;
	for (i = 0; i < NUMELS; i++)    // Print the prices

		cout << "price [" << i << "] is " << *(prices + i) << endl;

	system("PAUSE");
	return 0;

}

b. Repeat Exercise 6b in Section 7.1, but use pointer references to access all array elements.

#include <iostream>
using namespace std;

int main()

{
	const int NUMELS = 9;
	int i, prices[NUMELS];
	for (i = 0; i < NUMELS; i++)    // Enter the grades

	{
		cout << "Enter a price: ";
		cin >> *(prices +i);

	}
	cout << endl;

	for (i = 0; i < 3; i++) {   // Print the grades

		cout << *(prices + i) << " ";

	}
	cout << endl;

	for (i = 3; i < 6; i++) {   // Print the grades

		cout << *(prices + i) << " ";

	}
	cout << endl;

	for (i = 6; i < NUMELS; i++) {   // Print the grades
		cout << *(prices + i) << " ";
	}
	cout << endl;

	system("PAUSE");
	return 0;
}

7. (Modify) Repeat Exercise 7 in Section 7.1, but use pointer references to access all array
elements.

#include <iostream>

using namespace std;

int main()

{
	const int NUMELS = 8;
	int i, grade[NUMELS], total = 0, average;

	for (i = 1; i <= NUMELS; i++)    // Enter the grades

	{
		cout << "Enter a grade: ";
		cin >> *(grade +i);

	}

	cout << endl;

	for (i = 1; i <= 8; i++) {   // Print the grades
		
		cout << *(grade + i) << " " << endl;
		total = total + *(grade + i);
		average = total / i;

	}

	cout << "The average is " << endl;
	cout << average << endl;

	system("PAUSE");

	return 0;

}

8. (Modify) As described in Table 8.2, the new operator returns the address of the first new storage
area allocated or returns NULL if there’s insufficient storage. Modify Program 8.8 to check
that a valid address has been returned before attempting to place values in the grades array.
Display an appropriate message if not enough storage is available.

#include <iostream>
#include <new>
using namespace std;
int main()
{
	int numgrades, i;
	
	cout << "Enter the number of grades to be processed : ";
	cin >> numgrades;
	int *grades = new int[numgrades];  // create the array
	
	for (i = 0; i < numgrades; i++)
	{
		if ( numgrades >= 20){
			cout << " Not enough storage or invalid address entered" << endl;
			goto end;
		}
		if (numgrades > 0 && numgrades < 20){
			cout << "  Enter a grade : ";
			cin >> grades[i];
		}
	}
	if (numgrades > 0 && numgrades < 20){
		cout << "\nAn array was created for " << numgrades << " integers\n";
		cout << "The values stored in the array are: ";
		for (i = 0; i < numgrades; i++)
			cout << "\n   " << grades[i];
		cout << endl;
		delete[] grades;   // return the storage to the heap
		// the [] is required for array deletions
	}
	else{ cout << "Nothing to show" << endl; }
	end:
	system("PAUSE");
	return 0;
}