Exercise 3.4 (Completed)

1. (Practice) For the following declaration statements, write one or more statements using the
cin object that causes the computer to pause while the user enters the appropriate data:
a. int firstnum;
cin >> firstnum;
b. double grade;
cin >> grade;
c. double secnum;
cin >> secnum;
d. char keyval;
cin >> keyval;
e. int month, years;
double average;
cin >> month >>years >> average;
f. char ch;
int num1,num2;
double grade1,grade2;
cin >> ch >> num1 >> num2 >> grade1 >> grade2;
g. double interest, principal, capital;
double price, yield;
cin >> interest >> principal >> capital >> price >> yield;
h. char ch,letter1,letter2;
int num1,num2,num3;
cin >> ch >> letter1 >> letter2 >> num1 >> num2 >> num3;
i. double temp1,temp2,temp3;
double volts1,volts2;
cin >> temp1 >> temp2 >> temp3 >> volts1 >> volts2;

2. (Program) a. Write, compile, and run a C++ program that displays the following prompts:
Enter the length of the room:
Enter the width of the room:
After each prompt is displayed, your program should use a cin object call to accept data from
the keyboard for the displayed prompt. After the width of the room is entered, your program
should calculate and display the area of the room. The area displayed should be calculated by
using the formula area = length × width and should be included in an appropriate message.

#include <iostream>
using namespace std;
int main(){
int area, length, width;
cout << "Enter the length of the room:" << endl;
cin >>length;
cout << "Enter the width of the room:" <<endl;
cin >> width;
area = lenght * width;
cout << area <<endl; 
return 0;
}

b. Check the area displayed by the program written for Exercise 2a by calculating the result
manually.
Done!!
3. (Program) a. Write, compile, and run a C++ program that displays the following prompts:
Enter the length of the swimming pool:
Enter the width of the swimming pool:
Enter the average depth of the swimming pool:
After each prompt is displayed, your program should use a cin statement to accept data from
the keyboard for the displayed prompt. After the depth of the swimming pool is entered, your
program should calculate and display the volume of the pool. The volume should be calculated
with the formula volume = length × width × average depth and be displayed in an output
message.

#include <iostream> 
using namespace std;
int main(){
int length, width, average,volume;
cout << "Enter the length of the swimming pool:" <<endl;
cin >> length; 
cout << "Enter the width of the swimming pool:" <<endl;
cin >> width;
cout << "Enter the average depth of the swimming pool: << endl;
cin >> average >> endl;
cout << volume << endl;
return 0;
}

b. Check the volume displayed by the program written for Exercise 3a by calculating the
result manually.
Done!!
4. (Program) Write, compile, and run a C++ program that displays the following prompt:
Enter the radius of a circle:
After accepting a value for the radius, your program should calculate and display the area of
the circle. (Hint : Area = 3.1416 × radius^2.) For testing purposes, verify your program by using
an input radius of 3 inches. After manually determining that your program’s result is correct,
use your program to complete the following chart:
Radius (in)            Area (sq. in)
1.0                    3.1416
1.5                    7.0686
2.0                    12.5664
2.5                    19.635     
3.0                    28.2744
3.5                    38.4846

#include <iostream> 
using namespace std;
int main(){
double Area,radius;
cout<< " Enter the radius of a circle: " << endl;
cin >> radius;
Area = 3.1416 * pow(radius, 2);
cout << Area << endl;
return 0;
5. (Program) a. Write a C++ program that first displays the following prompt:
Enter the temperature in degrees Celsius:
Have your program accept a value entered from the keyboard and convert the temperature
entered to degrees Fahrenheit, using this formula:
Fahrenheit = (9.0 / 5.0) × Celsius + 32.0
Your program should then display the temperature in degrees Fahrenheit with an output
message.
#include <iosteam>
using namespace std;
int main(){
double Fahrenheit, Celsius;
cout << "Enter the temperature in degress Celsius:" << endl;
cin >> Celsius;
Fahrenheit = (9/5) * Celsius + 32.0;
cout << Fahrenheit << endl;
return 0;
}
b. Compile and run the program written for Exercise 5a. To verify your program, use the following
test data and calculate the Fahrenheit equivalents by hand, and then use your program
to see whether you get the same results:
Test data set 1: 0 degrees Celsius 32
Test data set 2: 50 degrees Celsius 82
Test data set 3: 100 degrees Celsius 132
When you’re sure your program is working correctly, use it to complete the following chart:
Celsius Fahrenheit
45      77
50      82
55      87 
60      92
65      97 
70      102

6. (Program) a. Write, compile, and run a C++ program that displays the following prompts:
Enter the miles driven:
Enter the gallons of gas used:
After each prompt is displayed, your program should use a cin statement to accept data from
the keyboard for the displayed prompt. After the number for gallons of gas used has been
entered, your program should calculate and display the miles per gallon (mpg). This value
should be calculated with the formula miles per gallon = miles / gallons used and displayed in an
output message. Verify your program by using the following test data:
Test data set 1: miles = 276, gas = 10 gallons // 27.6 gallon
Test data set 2: miles = 200, gas = 15.5 gallons // 12.9032 gallon

#include <iostream>
using namespace std;
int main(){
double miles, gallons, gallon;
cout << "Enter the miles driven:" << endl;
cin >> miles;
cout << "Enter the gallons of gas used:" << endl;
cin >> gallons;
gallon = miles/gallons;
cout << gallon << endl;
return 0;
}
After finishing your verification, use your program to complete the following chart. (Make sure to
convert the miles driven to kilometers driven, convert gallons used to liters used, and then compute
the kilometers per liter. There are 1.61 kilometers per mile and 4.54609 liters per gallon.)
Miles Driven     Gallons Used       Mpg        Km Driven    Liters Used            Km/L
250              16.00              15.625     402.5        72.73744              5.5336  
275              18.00              15.2778    442.75       81.82962              5.41063  
312              19.54              15.9672    502.32       88.8305986            5.65481  
296              17.39              17.0213    476.56       79.0565051            6.02809     
b. For the program written for Exercise 6a, determine how many verification runs are required
to make sure the program is working correctly, and give a reason to support your answer.

Only one is required if you use a miles and gallon pattern that result in an answer 
that can't be easily created by mistake. Making the change of the function results being value very high.

7. (Program) a. Write, compile, and run a C++ program that displays the following prompts:
Enter a number:
Enter a second number:
Enter a third number:
Enter a fourth number:
After each prompt is displayed, your program should use a cin statement to accept a number
from the keyboard for the displayed prompt. After the fourth number has been entered, your
program should calculate and display the average of the numbers. The average should be
displayed in an output message. Check the average your program calculates by using the following
test data:
Test data set 1: 100, 100, 100, 100 // 100
Test data set 2: 100, 0, 100, 0     //  50

#include <iostream>
using namespace std;
int main(){
double number, second_number, third_number, fourth_number,average;
cout << "Enter a number:" << endl;
cin >> number;
cout << "Enter a second number:" << endl;
cin >> second_number;
cout << "Enter a third number:" << endl;
cin >> third_number;
cout << "Enter a fourth number:" << endl;
cin >> fourth_number;
average = (number + second_number + third_number + fourth_number)/ 4;
cout <<"\n" << average <<endl;
return 0;
}
After finishing your verification, use your program to complete the following chart:
Numbers                 Average
92, 98, 79, 85          88.5
86, 84, 75, 86          82.75
63, 85, 74, 82          76
b. Repeat Exercise 7a, making sure you use the same variable name, number, for each number
input. Also, use the variable sum for the sum of the numbers. (Hint: To do this, you can use
the statement sum = sum + number; after each number is accepted. Review the material
on accumulating in Section 3.1.)
#include <iostream>
using namespace std;
int main()
{
	double number, average, sum = 0;
	cout << "Enter a number:" << endl;
	cin >> number;
	sum = sum + number;
	cout << "Enter a second number:" << endl;
	cin >> number;
	sum = sum + number;
	cout << "Enter a third number:" << endl;
	cin >> number;
	sum = sum + number;
	cout << "Enter a fourth number:" << endl;
	cin >> number;
	sum = sum + number ;
	average = sum / 4;
	cout << "\n" << average << endl;
	system("PAUSE");
	return 0;
}
8. (Program) The perimeter, approximate surface area, and approximate volume of an in-ground
pool are given by the following formulas:
perimeter = 2 × (length + width)
volume = length × width × average depth
underground surface area = 2 × (length + width) × average depth + length × width
Using these formulas as a basis, write a C++ program that accepts the length, width, and average
depth measurements, and then calculates the pool’s perimeter, volume, and underground surface
area. In writing your program, make these two calculations immediately after entering the
input data: length × width and length + width. The results of these two calculations should be used,
as needed, in the assignment statements for determining the perimeter, volume, and underground
surface area without recalculating them for each equation.

#include <iostream>
using namespace std;
int main(){
double perimeter, volume, underground_surface_area, length, width, average_depth;
cout << "Enter length: " <<endl;
cin >> length;
cout << "Enter width: " << endl;
cin >> width;
cout << "Enter average depth: " << endl;
cin >> average_depth;
perimeter = 2 * (length + width);
cout << "Perimeter: " << perimeter <<endl; 
volume = length * width * average_depth;
cout << "Volume: " << volume << endl;
underground_surface_area = 2 * (length + width) * average_depth + length * width;
cout <<"Underground Surface area: " << underground_surface_area << endl;
return 0;
}

Verify your program’s results by doing a hand calculation, using the following test data: length = 25 feet, width = 15 feet, and
average depth = 5.5 feet. 

Perimeter: 80
Volume: 2062.5

Underground Surface Area: 815

After verifying that your program is working, use it to complete the following
chart:
Length         Width       Average      Perimeter      Volume      Underground
                           Depth                                   Surface Area
25             10          5.0          70             1250        600   
25             10          5.5          70             1375        635
25             10          6.0          70             1500        670
25             10          6.5          70             1625        705
30             12          5.0          84             1800        780
30             12          5.5          84             1980        822             
30             12          6.0          84             2160        864
30             12          6.5          84             2340        906
9. (Program) a. Write, compile, and run a C++ program to compute and display the value of the
second-order polynomial ax2 + bx + c for any user-entered values of the coefficients a, b, and c
and the variable x. Have your program display a message first to inform users what the program
does, and then display suitable prompts to alert users to enter data. (Hint: Use a prompt such
as Enter the coefficient of the x-squared term:.)
#include <math.h>
#include <iostream> 
using namespace std;
int main(){
double a,b,c,x,value;
cout << "Enter the coefficient of the x-squared term:" <<endl;
cin >> x;
cout << "Enter the coefficient of the a-squared term:" <<endl;
cout << "Enter the coefficient of the b-squared term:" <<endl;
cout << "Enter the coefficient of the c-squared term:" <<endl;
value = (a*pow(x,2)) + (b*x) + c;
cout << "The value of the second-order polynimical is:" << endl;
return 0;

b. Check the result of your program written for Exercise 9a by using the following test data:
Test data set 1: a = 0, b = 0, c = 22, x = 56  // 22
Test data set 2: a = 0, b = 22, c = 0, x = 2   // 44
Test data set 3: a = 22, b = 0, c = 0, x = 2   // 88
Test data set 4: a = 2, b = 4, c = 5, x = 2    // 21

After finishing your verification, use your program to complete the following chart:
a            b                c               x                   Polynomial Value (ax2 + bx + c)
2.0          17.0            -12.0            1.3                 13.48
3.2          2.0              15.0            2.5                 40
3.2          2.0              15.0           -2.5                 30
-2.0         10.0              0.0            2.0                 12
-2.0         10.0              0.0            4.0                 8 
-2.0         10.0              0.0            5.0                 0
-2.0         10.0              0.0            6.0                -12 
5.0          22.0             18.0            8.3                 545.05
4.2          -16             -20             -5.2                 175.768

10. (Program) Write, compile, and run a program that calculates and displays the square root
value of a user-entered real number.

#include <iostream>
#include <math.h>
using namespace std;
int main(){
float number,square;
cout << Enter number to be squared<<endl;
cin << number;
square = sqrt(number);
cout << square <<endl;
return 0;
}

Verify your program by calculating the square roots of this
test data: 25, 16, 0, and 2.

5,4,0,1.41421 repectively

After finishing your verification,use your program to determine 
the square roots of 32.25, 42, 48, 55, 63, and 79.

5.67891, 6.48074, 6.9282, 7.4162, 7.93725,8.88819

11. (Program) Write, compile, and run a program to calculate and display the fourth root of a
user-entered number. Recall from elementary algebra that you find the fourth root of a number
by raising the number to the 1⁄4 power. (Hint : Don’t use integer division—can you see
why?) 
#include <iostream>
#include <math.h>
using namespace std;
int main(){
double number, solution;
cout << "Enter number to be forth-squared:"<< endl;
cin >> number;
solution = pow(number,(.25));
cout << "The solution is " << solution <<endl;
return 0;
}

Verify your program by calculating the fourth root of this test data: 81, 16, 1, and 0. 
3,2,1,0 respectively
When you’re finished, use your program to determine the fourth root of 42, 121, 256, 587, 1240, and
16,256.

2.54573, 3.31662,4,  4.9222, 5.93411 respectively

12. (Program) Program 3.12 prompts users to input two numbers; the first value entered is stored
in num1, and the second value is stored in num2. Using this program as a starting point,
write a program that swaps the values stored in the two variables.

#include <iostream>
using namespace std;
int main()
{
  double num1, num2, product;
  cout << “Please type in number 1: “;
  cin  >> num1;
  cout << “Please type in number 2: “;
  cin  >> num2;
  swap(num1,num2);
  cout << "New num1 " << num1 << endl;
  cout << "New num2 " << num2 << endl;
  return 0;
}

13. (Program) Write a C++ program that prompts users to enter a number. Have your program
accept the number as an integer and display the integer immediately by using a cout statement.
Run your program three times. The first time, enter a valid integer number; the second
time, enter a double-precision number; and the third time, enter a character. Using the output
display, see what number your program actually accepted from the data you entered.

#include <iostream>
using namespace std;
int main(){
int number;
cout << "Enter your number" << endl;
cin >> number;
cout << number << endl;
return 0;
}
First time:  Input: 5     Output: 5
Second time: Input: 3.45  Output: 3
Third time:  Input: Cat   Output: -858993460

14. (Program) Repeat Exercise 13, but have your program declare the variable used to store the
number as a double-precision variable. Run the program three times. The first time, enter an
integer; the second time, enter a double-precision number; and the third time, enter a character.
Using the output display, keep track of what number your program actually accepted from
the data you entered. What happened, if anything, and why?

The double-precision variable was able to send the correct numbers back for the first two runs. 
The third run sent out useless data because the complied did not know what to do with it. 

#include <iostream>
using namespace std;
int main(){
double number;
cout << "Enter your number" << endl;
cin >> number;
cout << number << endl;
return 0;
}
First time:  Input: 5     Output: 5
Second time: Input: 3.45  Output: 3.45
Third time:  Input: Cat   Output: -9.25596e+061

15. (For thought) a. Why do you think successful programs contain extensive data-input validity
checks? (Hint: Review Exercises 13 and 14.)

The program contain extensive data-input validity checks because 
they must be able to display information in a particual way in order to pass all test cases.

b. What do you think is the difference between a data-type check and a data-reasonableness
check?

A data type check checks the data type and how much control over the varable it has
while the dat-resonablenees check checks if the data is even understandable.

c. Assume that a program requests users to enter a month, day, and year. What are some checks
that could be made on the data entered?

check that the month is a character type
check that the day is an integer type
check that the year is an integer type