This document contains code for multiple C++ programs that demonstrate various concepts. The first section shows code for a time conversion program that converts between military and standard time formats. The second section shows code for a cookie sales tracking program that uses vectors to store cookie names and sales amounts, and includes functions to calculate totals, percentages, and find best/worst sellers. The third section covers various aspects of the C++ string data type, including initialization, input/output, concatenation, comparison operators, and common string methods.

1. //Lab Assignment #6, part 3: Time Conversion
//Program Name: lab6Part3
//Purpose of the program: converts time from military format to
civilian format
//Authors: Wei Zhou and Shouwen Wang
//Date: 02/19/2016
#include<iostream>
#include <string>
using namespace std;
// get input time
int enterTime(int totalTime, int& hrVal, int& minVal)
{
cout << "please enter a military time(a value between 0000 and
2359) : ";
cin >> totalTime;

2. while (totalTime > 2359 || totalTime < 0) {
cout << "Error: you entered an invalid time. Try again." <<
endl;
cout << "please enter a military time(a value between 0000 and
2359) : ";
cin >> totalTime;
}
return totalTime;
}
//perform conversion
int ConvHrMin(int totalTime, int& hrVal, int& minVal) {
if (totalTime <= 1200) {
hrVal = totalTime / 100;
minVal = totalTime % 100;
}
else {

3. hrVal = totalTime / 100 - 12;
minVal = totalTime % 100;
}
return hrVal, minVal;
}
//display results
void finalOutput(){
int totalTime = 0;
int hrVal;
int minVal;
string morning;
string noon;
morning = "AM";

4. noon = "PM";
totalTime = enterTime(totalTime, hrVal, minVal);
hrVal = ConvHrMin(totalTime, hrVal, minVal);
minVal = ConvHrMin(totalTime, hrVal, minVal);
if (totalTime <= 1200) {
cout << "Time in civilian format£º " << hrVal << ':' << minVal
<< " " << morning << endl;
}
else {
cout << "Time in civilian format£º " << hrVal << ':' << minVal
<< " " << noon << endl;
}
}
int main()
{

5. cout << "Time Converter" << endl;
cout << "--------------" << endl;
finalOutput();
cout << endl;
return 0;
}
//Lab Assignment #7: Vectors
//Program Name: lab7part1
//Purpose of the program: working with vectors
//Authors: Wei Zhou
//Date: 03/03/2016
#include<iostream>

6. #include<iomanip>
#include<vector>
#include<string>
using namespace std;
//enter the number of boxes sold for each type of cookie
void numberSell(vector<string> cookienames, vector<int>
&amount) {
int numberSales;
for (int i = 0; i < cookienames.size(); ++i)
{
cout << "Please enter the total sales for " << cookienames[i] <<
": ";
cin >> numberSales;
while (numberSales < 0) {

7. cout << "Error: total sales cannot be a negative number." <<
endl;
cout << "Please enter the total sales for " << cookienames[i] <<
": ";
cin >> numberSales;
}
amount.push_back(numberSales);
}
cout << endl;
}
//calculate total sales
int totalSales(vector<int> amount) {
int total = 0;
for (int i = 0; i < amount.size(); ++i)
{
total += amount[i];
}

8. return total;
}
//find the lowest selling cookie
string findBest(vector<string> cookienames, vector<int>
amount) {
int highest = amount[0], exponent = 0;
for (int i = 1; i<amount.size(); ++i)
{
if (amount[i] >= highest)
{
highest = amount[i];
exponent = i;
}
}
return cookienames[exponent];
}
//find the highest selling cookie

9. string findWorst(vector<string> cookienames, vector<int>
amount) {
int lowest = amount[0], exponent = 0;
for (int i = 1; i<amount.size(); ++i)
{
if (amount[i] <= lowest)
{
lowest = amount[i];
exponent = i;
}
}
return cookienames[exponent];
}
//calculate percentages of sales
vector<double> findPercentage(vector<int> amount, int total) {
double percentage;
vector<double> line;

10. for (int i = 0; i < amount.size(); ++i)
{
percentage = amount[i] * 100 / total;
line.push_back(percentage);
}
return line;
}
//display report
void finalResult(vector<string> cookienames, vector<int>
amount, int total, vector<double> percentage, string best, string
worst) {
cout << left << setw(30) << "Type of Cookie" << setw(25) <<
"Boxes Sold" << "Percentage" << endl;
cout << "---------------------------------------------------------------"
<< endl;
for (int i = 0; i < cookienames.size(); ++i)
{

11. cout << fixed << setprecision(2);
cout << left << setw(30) << cookienames[i] << setw(25) <<
amount[i] << setw(9) << percentage[i] << "%" << endl;
}
cout << endl;
cout << "Total number of boxes sold this month: " << total <<
endl;
cout << left << setw(45) << "Best seller cookie: " << best <<
endl;
cout << left << setw(45) << "Worst seller cookie: " << worst <<
endl;
cout << endl;
}
int main()
{
cout << "Cookie sales tracking program" << endl;
cout << "-------------------------------" << endl;

12. //declare and initialize vectors as needed
vector<string> cookienames = { "Thin Mints", "Tagalongs",
"Shortbread", "Lemonades", "Caramel deLites", "Do-si-dos",
"Thanks-A-Lot",
"Rah-Rah Raisins", "Toffee-tastic", "Cranberry Citrus Crisps",
"Trios", "Savannah Smiles" };
void numberSell(vector<string> cookienames, vector<int>&
amount);
int totalSales(vector<int> amount);
string findBest(vector<string> cookienames, vector<int>
amount);
string findWorst(vector<string> cookienames, vector<int>
amount);
vector<double> findPercentage(vector<int> amount, int total);

13. void finalResult(vector<string> cookienames, vector<int>
amount, int total, vector<double> percentage, string best, string
worst);
vector<int> amount;
int total;
string best, worst;
vector<double> percentage;
numberSell(cookienames, amount);
total = totalSales(amount);
worst = findWorst(cookienames, amount);
best = findBest(cookienames, amount);
percentage = findPercentage(amount, total);
finalResult(cookienames, amount, total, percentage, best,
worst);
Chapter 8
Strings
Random Numbers

14. Enumerated Types
The string Type
The string data type
To hold text data, such as a person's name or e-mail address,
C++ uses the string type.
The string type is kept in its own library:
#include <string>
A string variable is created just like any other variable:
string variableName;
A string variable may be initialized upon declaration in the
usual fashion.
Input and output of strings is just like any other variable type.
Examples
Declaring and initializing a string variable:
string today = "Tuesday"; // initialization
string tomorrow; //an empty string ""
Input and Output:
cout << "I think today is " << today << endl;
cout << "What day do you think it is tomorrow? ";

15. cin >> tomorrow;
cout << "OK, so tomorrow is " << tomorrow << endl;
Reading text with multiple words
To read in text that contains spaces we use the getline():
getline (InputSource, destinationVariable);
getline() command will read in all information until it
encounters an end of line.
Note that using getline() after using >> can cause problems.
We can fix these problems using the method cin.ignore().
Example
cout << "Please enter your age: ";
int age;
cin >> age;
cout << "Please enter your full name: ";
cin.ignore();
string fullName;
getline (cin, fullName);
cout << "Thank you, " << fullName << ". ";
cout << "Your are " << age << “ years old.";
Assignment and concatenation
The = sign is used for assignment, just as with other variables.
That is, the value of the expression on the right of the = is
assigned to the variable on the left.

16. The + operator concatenates two strings
That is, it appends one string to the end of another.
Example
string day = "Tuesday";
cout << "Today is " << day << "." << endl;
string date = "March 8";
cout << "Today is " << date << "." << endl;
date = day + ", " + date;
cout << "Today is " << date << "." << endl;
The segment of code about will output:
Today is Tuesday.
Today is March 8.
Today is Tuesday, March 8.
The index system
A string is a collection of characters.
Each character inside a string has an index indicating its
location inside the string.
The first character in the string has index zero. The last
character has an index one less than the size of the string.
The subscript operator
In order to access a character inside a string we can use the

17. subscript operator [] and a valid index value.
Example:
string course = "CS 143";
char firstLetter = course[0]; //C
char lastChar = course[5]; // 3
Comparing Strings
The relational operators can be used to compare strings.
Example:
string name1 = "Mary";
string name2 = "Mark";
if ( name1 == name2 )
cout << "The names are the same" ;
else if ( name1 < name2 )
cout << "In alphabetical order: "
<< name1 << " " << name2 ;
else
cout << "In alphabetical order: "
<< name2 << " " << name1 ;
11
How does string comparison work?
In memory characters are stored using numeric codes.
The most commonly used code is ASCII: http://asciiset.com/
Each letter (a-z, A-Z), digit (0-9), and other characters have a
code associated with them:

18. ‘A’ – ‘Z’: codes 65 – 90
‘a’ – ‘z’: codes 97 – 122
‘0’ – ‘9’ : codes 48 – 57
When the relational operators compare two strings:
They compare the strings character-by-character
They actually compare the codes for the characters
12
Example
If one of the strings in a comparison is shorter than the other
one, only the corresponding characters are compared.
If the corresponding characters are identical, the shorter string
is consider less than the longer string
Mary > Mark because: y > k
or in other words: 121 > 107
121
107
114
97
77
114
97
77
ASCII Codes
String Methods
The string type comes with a collection of very useful methods.

19. Remember that in order to invoke a method your must use the
dot notation.
Some methods return values and some don’t
Some methods have parameters and some don’t
returnValue = stringObject.methodName(arguments);
length() and size()
Both of these methods return the number of characters in the
string.
The count will include blank space and special characters if the
string contains these.
The type of the returned value is int.
Example
string course = "CS 143";
cout << "The string " << course << " has "
<< course.size()
<< " characters (including blanks). " ;
cout << "That means " << course.length() - 1
<< " letters.";
The at() method
Another way to access the characters in a string is the at(index)
method.
This method takes as its input a valid index value
This method returns the character (char) at the given index
value.
Example:
string course = "CS 143";
char firstLetter = course.at(0); //C
char lastChar = course.at(course.size() -1); // 3

20. The clear() and empty() methods
The clear() method removes all the elements in a string (and
resets its size to zero).
The empty() method returns true if the string is empty, false
otherwise.
Example:
string course = "CS 143";
course.clear(); //now course is an empty string ""
if ( course.empty() )
cout << "There are 0 characters in the string";
push_back()and append() methods
push_back(newChar): appends the char newChar to the end of
the string.
append(secondStr): appends a copy of the string secondString.
Example:
string course = "CS 143";
course.append(" C++"); //course is now: CS 143 C++
course.push_back('!'); //course is now: CS 143 C++!
The replace() method
replace(index, num, subString) replaces num characters starting
at index with a copy of the string subString.
Example:
string course = "CS 143";
course.replace(3, 3, "171"); //course is now: CS 171

21. erase(), insert()and resize() methods
erase(index, n) deletes n characters of the string, starting at
index.
insert(index, subStr) inserts the string subStr starting at index.
resize(newSize) resizes the string to have newSize characters.
If decrease, drops extra characters.
If increase, sets new characters to null ('0', ASCII value 0).
Example:
string course = "CS 143";
course.erase(2, 1); //course is now: CS143
course.insert(2, "---"); //course is now: CS---143
course.resize(2); //course is now: CS
Searching a string
You can use the find() method to search for a substring in a
string.
There are two ways you can use the find() method:
find(item)
find(item, startPoint)
Item: the substring we are looking for
startPoint: an index where to start the search
This method returns the index of the first occurrence if item in
the string (if found). Otherwise it returns -1
Searching a string
The rfind() method works similar to find() except that it starts
the search from the end/back of the string and searches
backwards through the string to the beginning/front.
rfind stands for reverse find.

22. Example: find()
string course = "CS 143";
int location, secondS;
location = course.find("143"); //location = 3
location = course.find("171"); //location = -1
location = course.find("S"); //location = 1
secondS = course.find("S",location + 1); //secondS = -1
Example: rfind()
string course = "CS 143";
int location, secondS;
location = course.rfind("143"); //location = 3
location = course.rfind("171"); //location = -1
location = course.rfind("S"); //location = 1
secondS = course.rfind("S",location - 1);//secondS = -1
Obtaining substrings
The subsrt() method allows you to obtain a substring from a
string.
subsrt(index, howMany);
Index: the index of the first character to obtain
howMany: how many characters to obtain
This method returns a string.

23. Example
string course = "CS 143";
int blankPos;
blankPos = course.find(" "); // blankPos = 2
string subject, number;
subject = course.substr(0, blankPos); //get 2 chars
int qty = course.size() – blankPos - 1; //qty = 3
number = course.substr(blankPos + 1, qty); //get 3 chars
Character operations
The ctype library provides access to several functions for
working with characters
To access the functions you must use the directive:
#include <ctype>
FunctionDescriptionExampleisalpha(character)Returns true if
character is a letter (a-z or A-Z)isalpha('A') // true
isalpha('7') // falseisdigit(character)Returns true if character is a
digit (0-9)isdigit('A') // false
isdigit('7’) // trueisspace(character)Returns true if character is a
whitespaceisspace(' ') // true
isspace('n') // true
isspace('x') // falsetoupper(character)Returns a uppercase
version of the charactertoupper('a') //
Atolower(character)Returns a lowercase version of the
charactertolower('A') // a
Random Numbers

24. Random Numbers
Random number: an unpredictable number
-random numbers but close
enough
To generate random numbers we need functions and features
from the cstdlib header file
The rand() function:
Returns a random number between 0 and RAND_MAX
RAND_MAX is an integer constant defined in cstdlib
RAND_MAX = 32767
Random Numbers
In order to generate a random number within a given range
[upper, lower] we will use this formula:
int n = (upper–lower+1)*(rand()/(RAND_MAX+1.0))+lower;
Example: Generate random numbers between 1 and 6 (to
simulate rolling a die for example)
int n = (6 – 1 + 1) * ( rand()/(RAND_MAX+1.0) ) + 1;
int n = ( 6 ) * ( rand()/(RAND_MAX+1.0) ) + 1;
int n = 6 * [0, 0.999] + 1 ;
Note: for the example we are testing the edge cases

25. More Examples
[10, 20]
int n = (11) * (rand() / (RAND_MAX + 1.0)) + 10 ;
int n = 11 * [0, 0.999] + 10 ;
[-10, 15]
int n = (15–(-10)+1)*(rand()/(RAND_MAX+1.0))+(-10);
int n = 26 * [0, 0.999] - 10 ;
int n = 26 * 0 – -10
int n = 26 * (0.999) – –
Reproducible/Irreproducible Sequences
rand() uses an internal formula to produce random numbers
That formula has a value, called the seed, which is used to
produce the first random number.
The next random number is generated based on the first random
number.
The next random number is generated based on the previous
random number.
Consequence: for a given seed, the sequence of random
numbers is always the same.
Changing the seed
The srand(int) function allows us to change the value of the
seed.
But the value of the seed should be changed each time we run
the program.
We will use the help of the time() function from the ctime

26. library:
time(0) returns the number of seconds that have passed since
January 1, 1970 0:0:0 GMT and the machine’s current time.
int seed = static cast<int>( time(0) ) ;
srand(seed)
Example
#include <ctime>
#include <cstdlib>
#include <iostream>
using namespace std;
int main ()
{
int seed = static_cast<int>( time( 0 ));
srand( seed );
cout << "Here is a sequence of 5 random numbers: ";
for (int i = 1; i <= 5 ; i++)
cout << rand() << " " ;
return 0;
}
Enumerated Types

27. Enumerated types
The enum command allows us to create simple new data types
Types created with enum have a limited set of values (or
names).
These values are really nothing more than const ints, so it's
common practice to write them all in caps.
Once the new type is created, it behaves (more or less) like any
other type.
You create variables of that type and assign it values from the
list.
Declaring Enumerated Types
The generic format of enum is:
enum TypeName {value1, value2, value3, ... };
Examples:
enum Direction {NORTH, SOUTH, EAST, WEST};
enum Color {RED, BLUE, YELLOW, BLACK, WHITE};
enum Season {FALL, WINTER, SPRING, SUMMER};
Note that each value is an identifier, not a string.
By convention an enumerated type is named with the first letter
of each word capitalized and a value of an enumerated type is
named like a constant with all uppercase letters.
Declaring variables
Once a type is defined, you can declare a variable of that type:
Season current;
The variable forward can hold one of the values defined in the
enumerated type.
current = WINTER;

28. As with any other type, you can declare and initialize a variable
in one statement:
Season current = WINTER;
Enumerated values
Enumerated values are stored as integers in memory.
By default the values correspond to 0, 1, 2….., in order of their
appearance in the list.
Example:
enum Season {FALL, WINTER, SPRING, SUMMER};
FALL corresponds to the integer value 0, WINTER to 1,
SPRING to 2, and SUMMER to 3.
Enumerated values
You can explicitly assign an enumerated value with any integer
value.
Example:
enum Season {FALL = 20, WINTER = 30,
SPRING = 40, SUMMER = 50};
If you assign integer values for some values in the enumerated
type declaration, the other values will receive default values.
Example:
enum Season {FALL, WINTER, SPRING = 40, SUMMER};
FALL corresponds to the integer value 0, WINTER to 1,
SPRING to 40, and SUMMER to 41.

29. Manipulating enumerated types
One popular way of manipulating a variable of an enumerated
type is with the switch statement.
Example:
switch (current)
{
case FALL:
//process FALL
break;
case WINTER:
//process WINTER
break;
…etc…
}
What the new type can do
Simple Assignment
Season current = WINTER ;
current = SPRING ;
Season next = current ;
Simple Comparison (== and !=)
if (forward == sunrise)
cout << "You watch an inspiring sunrise." << endl;
What the new type can do, cont.

30. Used in functions as parameters and return values.
Season next_season (season current)
{
switch (current)
{
case FALL:
return WINTER;
case WINTER:
return SPRING;
case SPRING:
return SUMMER;
case SUMMER:
return FALL;
}
}
What the new type cannot do
Other math operators do not make sense:
Season current = WINTER;
current = current * 10 ;
Comparison based on inequality (<, <=, >. >=) works, but is
often meaningless:
Season next = SPRING ;
if (current >= next )
Produce meaningful output using <<:
cout << "This is the " << current << " season";
//This line produces output such as "This is the 0 season"

31. Helper functions
One way to work around the issue with output operator is to use
a helper function
string season_name (Season s)
{
switch (s)
{
case FALL:
return "Fall";
case WINTER:
return "Winter";
case SPRING:
return "Spring";
case SUMMER:
return "Summer";
}
}
cout << "This is the " << season_name(current) << " season";
CS 143 Final Exam
Date:Tuesday March 15, 2016
Time:3:30 PM – 5:30 PM
Room:Disque 103
Bring:
your Drexel student ID
If you do not bring your Drexel ID I will not accept your exam.
Pen/pencil/eraser
Study guide available in Learn
Problets available to study for the final

32. Assignments for this week
Lab 9 is due at the end of the lab session or by Friday 11:59 PM
at the latest.
Hard deadline: you and your partner will not be able to submit
after the deadline.
Lab must be submitted via Bb Learn. Submissions via email will
not be accepted or graded
Submit the source code as a cpp file. No other formats will be
graded.
CodeLab assignment # 9:
Due on Tuesday, March 15 by 11:59 PM
Submit your proof of completion via Bb Learn
Hard deadline: your answers will not be recorded after the
deadline.
zyBook Chapter 7: Participation and Challenge Activities
Due on Monday March 15 by 11:59 PM
Hard deadline: late submissions will not be graded
CS 143 Laboratory Exercise 9
Purpose:
The purpose of this lab is to gain practical experience with
strings, random number, and
enumerated types.
Contents:

33. I. Startup
II. Course Evaluation
III. String and Character manipulation
IV. Random Numbers and enumerated types
I. Startup:
You will work with your lab partner to find the solutions to the
proposed problems. At the
end of the lab session your group should submit the code your
write today via Drexel Learn.
Only one submission per group is required. Make sure you and
your partner agree on who
will be responsible for submitting your lab assignment for this
week.
Note: It is important that both partners participate in the
programming process for
the entire assignment. One student shouldn't hog the machine,
or bully the others into
doing things a certain way. Try to act professional when
working with your partners - treat
them with the respect of knowledgeable co-workers on a job.
II. Course Evaluation:
Please take a few minutes to complete the College of Computing
and Informatics course
evaluation form. The form is available at:
https://cci.drexel.goaefis.net/index.cfm
Each student must complete the course evaluation form before

34. starting the lab exercise.
NOTE: The completion of the course evaluation form is part of
you grade for this lab, so
please make sure you show the lab instructor that you completed
the evaluation form. We
will make a list of the students who complete the evaluation so
they can receive full
credit for the lab.
III. String and Character manipulation:
Start up a new project for today’s lab. If you are working on
one of the classroom
laptops, it’s recommended that you save your project in the
Desktop.
Add the following header comment at the top of the file:
//Lab Assignment #9, Characters and Strings manipulation
//Program Name:
//Purpose of the program:
//Authors: Your and your partner’s names
//Date: write today’s date
Write a program that will check a new password and make sure
it’s valid. The program
will start by asking the user to enter his/her full name (as one
string that is, the full name
must be store in one string variable), and then his/her login ID
(also a string variable).
Then the program as the user to enter a new password and

35. validates it. Here is the criteria
for valid passwords:
following four categories:
– Z).
– z).
– 9).
-alphabetic characters (for example: @ # $ % ^ & * - + =
| { ] ? / etc.).
by the last name initial)
If the password entered by the user meets the all criteria the
program let’s the user know
that the password has been changed. If the password entered
does not meet at least one of
the criteria, the program issues an error message and ask the
user to try again (as many
time as needed unti lthe user provides a valid password).
You should consider writing functions to solve this problem,
othewise you may end up

36. with a very long main function.
Here is a typical sample run for the program:
IV. Random Numbers and enumerated types:
Remove the current cpp file from the project, following these
steps:
1) In the
Solution
Explorer, find the Source Files folder and then your cpp file.
2) Right-click on the name of your cpp file. You will see a
menu pop-up. Pick the
Remove option. You will see a confirmation window. Click on
the Remove button.
3) Now add a New Item, by right-clicking the Source File folder
and then Add New
Item

37. 4) At Add New Item dialog box select C++ File (.cpp)). Give
this file a name and then
click on the Add button.
Your source code must include the following header comment at
the top of the file:
//Lab Assignment #9, Random Numbers and enumerated types
//Program Name:
//Purpose of the program:
//Authors: Your and your partner’s names
//Date: write today’s date
For this part of the lab we are going to implement a simple
guessing game that the user
can play against the computer. Start by creating an enumerated
type to represent fruits
(have at least 10 fruits of your choice listed). Generate a
random number between 0 and
9 – this number will be used to access a “random” fruit from the
list. This will be the
computer choice. The program will ask the user to guess the
name of the fruit the

38. computer has picked. The user then enters a guess. If the user
is right he/she wins.
Otherwise the computer wins. The user can play as many times
as he/she wants. Once
the user decides to quit the game, display the tally, that is, the
number of times the
computer won and the number of times the player won.
This program must be implemented using enumerated types.
You must write at least two
functions: One to handle the input of a fruit as an enumerated
type; and one to handle the
display of a fruit name. Here is a typical sample run for the
program:
Submitting your lab work
For today’s lab your group must submit the .cpp files for the
programs you wrote
today. Please make sure you upload and submit your files via

39. Drexel Learn by the
end of the lab session, or by Friday at 11:59 PM at the latest.
Submissions via email will
not be graded.
For the programs: Do not copy and paste you code in a Word
file (or any other type of
document). Only cpp files will be read and graded.