Week 3 (CS 200)

1. Class schedule
2. Assignment links
3. Example code

Structs, branching, strings

1. Class schedule

Tuesday: Boolean logic, If statements, Switch statements, Lab - program 1
Thursday: Structs, Strings, Lab - programs 2 and 3

2. Assignment links

Assignment	Reading link	Canvas link
📚 Intro: Boolean logic	Read	Canvas quiz
📚 Intro: If statements	Read	Canvas quiz
📚 Intro: Switch statements	Read	Canvas quiz
📚 Intro: Structs	Read	Canvas quiz
📚 Intro: String library	Read	Canvas quiz
💾 Lab: Branching, structs, and strings	Read	Canvas assignment
💬 Discussion: User Interfaces		Canvas discussion
🙆 Update: Week 3		Canvas assignment

3. Example code

3.1. Branching

3.1.1. Standalone if: Absolute value

#include <iostream>
using namespace std;


int main() {
 float number;
 float absValue;


 cout << "Enter a value (positive or negative): ";
 cin >> number;
 absValue = number;


 if (number < 0) {
   absValue = -absValue;
 }


 cout << "The absolute value of " << number << " is " << absValue << endl;


 return 0;
}

3.1.2. If/else: Card declined?

#include <iostream>     // cin and cout
using namespace std;    // removes std:: prefix (std::cin, std::cout)


int main()
{
   float price;    // The price of some item
   float balance;  // The user's account balance


   cout << "What is your account balance: ";
   cin >> balance;


   cout << "How much does the item cost? ";
   cin >> price;


   // WAY 1:
   if ( price > balance )  // User doesn't have enough money
   {
       cout << "Card declined. :(" << endl;
   }
   else                    // User does have enough money
   {
       cout << "Card accepted! :)" << endl;
       balance = balance - price;
   }


   // WAY 2:
   if ( price <= balance ) // User does have enough money
   {
       cout << "Card accepted! :)" << endl;
       balance = balance - price;
   }
   else                    // User doesn't have enough money.
   {
       cout << "Card declined. :(" << endl;
   }


   cout << "Your balance is now: $" << balance << endl;

   return 0;
}

3.1.3. If/else if: Pizza builder

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


int main() {
 cout << "PIZZA HAT" << endl << endl;


 cout << "1. Cheese pizza" << endl;
 cout << "2. Pepperoni pizza" << endl;
 cout << "3. Pineapple + canadian Bacon pizza" << endl;
 cout << "4. Buffalo chicken pizza" << endl;
 cout << "5. Lotsa veggies pizza" << endl;
 cout << "6. Vegan veggies pizza" << endl;


 int pizzaChoice;
 cout << endl << "Which pizza would you like? ";
 cin >> pizzaChoice;


 const float BASE_PIZZA_PRICE = 9.00;
 const float VEGGIE_TOPPINGS_PRICE = 0.40;
 const float MEAT_TOPPINGS_PRICE = 0.50;
 const float CHEESE_PRICE = 0.30;
 const float SAUCE_PRICE = 0.25;


 float price;


 cout << fixed << setprecision( 2 );
 if ( pizzaChoice == 1 ) // Cheese pizza
 {
   cout << "Pizza ($" << BASE_PIZZA_PRICE << ") and:" << endl;
   cout << "  * Tomato sauce ($" << SAUCE_PRICE << ")" << endl;
   cout << "  * Cheese ($" << CHEESE_PRICE << ")" << endl;
   price = BASE_PIZZA_PRICE + SAUCE_PRICE + CHEESE_PRICE;
 }
 else if ( pizzaChoice == 2 ) // Pepperoni pizza
 {
   cout << "Pizza ($" << BASE_PIZZA_PRICE << ") and:" << endl;
   cout << "  * Tomato sauce ($" << SAUCE_PRICE << ")" << endl;
   cout << "  * Cheese ($" << CHEESE_PRICE << ")" << endl;
   cout << "  * Pepperoni ($" << MEAT_TOPPINGS_PRICE << ")" << endl;
   price = BASE_PIZZA_PRICE + SAUCE_PRICE + CHEESE_PRICE + MEAT_TOPPINGS_PRICE;
 }
 else if ( pizzaChoice == 3 ) // Pineapple / bacon pizza
 {
   cout << "Pizza ($" << BASE_PIZZA_PRICE << ") and:" << endl;
   cout << "  * Tomato sauce ($" << SAUCE_PRICE << ")" << endl;
   cout << "  * Cheese ($" << CHEESE_PRICE << ")" << endl;
   cout << "  * Pineapple ($" << VEGGIE_TOPPINGS_PRICE << ")" << endl;
   cout << "  * Canadian bacon ($" << MEAT_TOPPINGS_PRICE << ")" << endl;
   price = BASE_PIZZA_PRICE + SAUCE_PRICE + CHEESE_PRICE
+ VEGGIE_TOPPINGS_PRICE + MEAT_TOPPINGS_PRICE;
 }
 else if ( pizzaChoice == 4 ) // Buffalo chicken pizza
 {
   cout << "Pizza ($" << BASE_PIZZA_PRICE << ") and:" << endl;
   cout << "  * Tomato sauce ($" << SAUCE_PRICE << ")" << endl;
   cout << "  * Buffalo sauce ($" << SAUCE_PRICE << ")" << endl;
   cout << "  * Cheese ($" << CHEESE_PRICE << ")" << endl;
   cout << "  * Chicken ($" << MEAT_TOPPINGS_PRICE << ")" << endl;
   price = BASE_PIZZA_PRICE + SAUCE_PRICE + SAUCE_PRICE
+ CHEESE_PRICE + MEAT_TOPPINGS_PRICE;
 }
 else if ( pizzaChoice == 5 ) // Veggies
 {
   cout << "Pizza ($" << BASE_PIZZA_PRICE << ") and:" << endl;
   cout << "  * Tomato sauce ($" << SAUCE_PRICE << ")" << endl;
   cout << "  * Cheese ($" << CHEESE_PRICE << ")" << endl;
   cout << "  * Tomato ($" << VEGGIE_TOPPINGS_PRICE << ")" << endl;
   cout << "  * Black olives ($" << VEGGIE_TOPPINGS_PRICE << ")" << endl;
   cout << "  * Mushrooms ($" << VEGGIE_TOPPINGS_PRICE << ")" << endl;
   price = BASE_PIZZA_PRICE + SAUCE_PRICE + CHEESE_PRICE
+ VEGGIE_TOPPINGS_PRICE + VEGGIE_TOPPINGS_PRICE + VEGGIE_TOPPINGS_PRICE;
 }
 else if ( pizzaChoice == 6 ) // Vegan
 {
   cout << "Pizza ($" << BASE_PIZZA_PRICE << ") and:" << endl;
   cout << "  * Tomato sauce ($" << SAUCE_PRICE << ")" << endl;
   cout << "  * Tomato ($" << VEGGIE_TOPPINGS_PRICE << ")" << endl;
   cout << "  * Black olives ($" << VEGGIE_TOPPINGS_PRICE << ")" << endl;
   cout << "  * Mushrooms ($" << VEGGIE_TOPPINGS_PRICE << ")" << endl;
   price = BASE_PIZZA_PRICE + SAUCE_PRICE + VEGGIE_TOPPINGS_PRICE
+ VEGGIE_TOPPINGS_PRICE + VEGGIE_TOPPINGS_PRICE;
 }


 cout << endl << "TOTAL PRICE: $" << price << endl;


 return 0;
}

3.1.4. Nested if statement: Restaurant

#include <iostream>     // cin and cout
using namespace std;    // removes std:: prefix (std::cin, std::cout)


int main()
{
   float price;
   int menuChoice, age;


   cout << "RESTAURANT" << endl;
   cout << "1. Hamburger ($10)" << endl;
   cout << "2. Fries     ($5)" << endl;
   cout << "3. Beer      ($12)" << endl;
   cout << "4. Soda      ($4)" << endl;
   cout << "What do you want to order? ";
   cin >> menuChoice;


   if ( menuChoice == 1 ) { // hamburger
       price = 10;
   }
   else if ( menuChoice == 2 ) { // fries
       price = 5;
   }
   else if ( menuChoice == 3 ) { // beer
       cout << "What is your age? ";
       cin >> age;


       // Card the user
       if ( age >= 21 ) {
           price = 12;
       }
       else {
           cout << "You can't have any beer." << endl;
           price = 0;
       }
   }
   else if ( menuChoice == 4 ) { // soda
       price = 4;
   }


   cout << endl << "Price: $" << price << endl;


   return 0;
}

3.1.5. Logic operators: Milk, eggs, and cheese

#include <iostream>
using namespace std;


int main()
{
   bool milk, cheese, eggs;


   cout << "Do you have milk? (0 = false, 1 = true): ";
   cin >> milk;


   cout << "Do you have cheese? (0 = false, 1 = true): ";
   cin >> cheese;


   cout << "Do you have eggs? (0 = false, 1 = true): ";
   cin >> eggs;


   cout << endl;


   // Using AND
   if ( cheese && eggs ) {
       cout << "Make an cheese omelette" << endl;
   }
   else if ( milk && cheese ) {
       cout << "Make macaroni" << endl;
   }
   else {
       cout << "Go to the grocery store" << endl;
   }


   // Using OR
   if ( milk || cheese ) {
       cout << "You have dairy in the fridge" << endl;
   }
   else // Opposite of ( milk || cheese ) == !( milk || cheese )
   {    //                                == !milk && !cheese


                     cout << "You have no dairy in the fridge" << endl;
   }

   return 0;
}

3.1.6. Switch statement: Sandwich shop

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


int main() {
 cout << "SANDWICH SHOP" << endl;
 cout << "1. Grilled Cheese" << endl;
 cout << "2. BLT" << endl;
 cout << "3. Turkey Club" << endl;


 cout << endl << "Your choice: ";


 int choice;
 cin >> choice;


 float price;


 cout << endl;


 switch (choice) {
 case 1:
   cout << "GRILLED CHEESE SELECTED" << endl;
   price = 5.99;
   break;


 case 2:
   cout << "BLT SELECTED" << endl;
   price = 6.95;
   break;


 case 3:
   cout << "TURKEY CLUB SELECTED" << endl;
   price = 6.50;
   break;


 default:
   cout << "INVALID SELECTION" << endl;
 }


 cout << fixed << setprecision(2);
 cout << endl << "Price: $" << price << endl;


 return 0;
}

3.2. Structs

3.2.1. Basic struct: Menu items

#include <iostream>
#include <iomanip>
#include <string>
using namespace std;

struct MenuItem
{
 string name;
 float price;
};

int main() {

 MenuItem item1, item2, item3;

 item1.name = "Burrito";
 item1.price = 1.29;
 item2.name = "Taco";
 item2.price = 1.19;
 item3.name = "Quesadilla";
 item3.price = 3.45;

 cout << fixed << setprecision(2);
 cout << "RESTAURANT" << endl << endl;
 cout << "1. $" << item1.price << "\t " << item1.name << endl;
 cout << "2. $" << item2.price << "\t " << item2.name << endl;
 cout << "3. $" << item3.price << "\t " << item3.name << endl;

 return 0;
}

3.2.2. Structs in structs: Building and rooms

#include <iostream>
#include <iomanip>
#include <string>
using namespace std;


struct Room
{
   string name;
   float width;
   float length;
   float area;
};


struct Building
{
   string name;
   float totalArea;
   Room room1;
   Room room2;
   Room room3;
};


int main()
{
   Building house;
   house.name = "House";
   house.totalArea = 0;


   house.room1.name = "Livingroom";
   house.room1.width = 15;
   house.room1.length = 20;
   house.room1.area = house.room1.width * house.room1.length;
   house.totalArea += house.room1.area;


   house.room2.name = "Bedroom";
   house.room2.width = 12;
   house.room2.length = 16;
   house.room2.area = house.room2.width * house.room2.length;
   house.totalArea += house.room2.area;


   house.room3.name = "Bathroom";
   house.room3.width = 6;
   house.room3.length = 10;
   house.room3.area = house.room3.width * house.room3.length;
   house.totalArea += house.room3.area;


   cout << "HOUSE INFORMATION" << endl << endl;
   cout << "Building:   " << house.name << endl;
   cout << "Total SQFT: " << house.totalArea << endl;


   cout << endl << "ROOM 1: " << house.room1.name << endl;
   cout << "* width:  " << house.room1.width << " ft" << endl;
   cout << "* length: " << house.room1.length << " ft" << endl;
   cout << "* area:   " << house.room1.area << " sqft" << endl;


   cout << endl << "ROOM 2: " << house.room2.name << endl;
   cout << "* width:  " << house.room2.width << " ft" << endl;
   cout << "* length: " << house.room2.length << " ft" << endl;
   cout << "* area:   " << house.room2.area << " sqft" << endl;


   cout << endl << "ROOM 3: " << house.room3.name << endl;
   cout << "* width:  " << house.room3.width << " ft" << endl;
   cout << "* length: " << house.room3.length << " ft" << endl;
   cout << "* area:   " << house.room3.area << " sqft" << endl;


   return 0;
}

3.3. Strings

3.3.1. Size

string size documentation

cout << "Please enter a string: ";
string text;


//cin >> text;          // stops at spaces
cin.ignore();
getline( cin, text );   // get a whole line of text (with spaces)


cout << "There are " << text.size() << " characters in the string." << endl;

3.3.2. Subscript operator [ ]

cout << "Please enter a string: ";
string text;
cin.ignore();
getline( cin, text );


cout << "The first letter is " << text[0] << endl;
cout << "The second letter is " << text[1] << endl;
cout << "The third letter is " << text[2] << endl;


if ( text[0] == 'H' )
{
   cout << "Are you typing Hello?" << endl;
}

3.3.3. Find

string find documentation

string text = "Hello, world!";


cout << "What do you want to search for? ";
string findme;
cin.ignore();
getline( cin, findme );


int findPosition = text.find( findme );


if ( findPosition == string::npos )
{
   cout << "String not found" << endl;
}
else
{
   cout << "String found at position " << findPosition << endl;
}

3.3.4. Substring

string substr documentation

string text = "Hello, world!";


cout << "Enter a starting position: ";
int start;
cin >> start;


cout << "Enter a length: ";
int length;
cin >> length;


string newString = text.substr( start, length );


cout << "The new string is: \"" << newString << "\"" << endl;

3.3.5. Compare

string compare documentation

string string1, string2;
cout << "Enter string 1: ";
cin.ignore();
getline( cin, string1 );


cout << "Enter string 2: ";
getline( cin, string2 );


int result = string1.compare( string2 );


if ( result == 0 )
{
   cout << "The strings are the same" << endl;
}
else if ( result < 0 )
{
   cout << string1 << " < " << string2 << endl;
}
else if ( result > 0 )
{
   cout << string1 << " > " << string2 << endl;
}

3.3.6. Concatenate

string concatenate documentation

cout << "EXAMPLE 1" << endl;
string string1, string2;
cout << "Enter string 1: ";
cin.ignore();
getline( cin, string1 );

cout << "Enter string 2: ";
getline( cin, string2 );

string string3 = string1 + string2;
cout << "Result: " << string3 << endl;

cout << endl << "EXAMPLE 2" << endl;
string text = "Hello";
cout << "Original text " << text << endl;

cout << "What do you want to append to the text: ";
string appendMe;
getline( cin, appendMe );

text += appendMe;
cout << "Text is now " << text << endl;

3.3.7. Insert

string insert documentation

string text = "HelloWorld";
cout << "Original text: \"" << text << "\"" << endl;


cout << "Enter a string to insert: ";
string insertMe;
cin.ignore();
getline( cin, insertMe );


cout << "Enter a position to insert at: ";
int insertLocation;
cin >> insertLocation;


text = text.insert( insertLocation, insertMe );


cout << "New text: \"" << text << "\"" << endl;

3.3.8. Erase

string erase documentation

string text = "HelloWorld";
cout << "Original text: \"" << text << "\"" << endl;


cout << "Enter a position to begin erasing at: ";
int start;
cin >> start;


cout << "Enter a length of chars to remove: ";
int length;
cin >> length;


text = text.erase( start, length );


cout << "New text: \"" << text << "\"" << endl;

3.3.9. Replace

string replace documentation

string text = "HelloWorld";
cout << "Original text: \"" << text << "\"" << endl;


cout << "Enter a position to begin erasing at: ";
int start;
cin >> start;


cout << "Enter a length of chars to remove: ";
int length;
cin >> length;


cout << "Enter a string to insert at that position: ";
string addMe;
cin.ignore();
getline( cin, addMe );


text = text.replace( start, length, addMe );


cout << "New text: \"" << text << "\"" << endl;

Week 3 (CS 200)

Table of Contents

1. Class schedule

2. Assignment links

3. Example code

3.1. Branching

3.1.1. Standalone if: Absolute value

3.1.2. If/else: Card declined?

3.1.3. If/else if: Pizza builder

3.1.4. Nested if statement: Restaurant

3.1.5. Logic operators: Milk, eggs, and cheese

3.1.6. Switch statement: Sandwich shop

3.2. Structs

3.2.1. Basic struct: Menu items

3.2.2. Structs in structs: Building and rooms

3.3. Strings

3.3.1. Size

3.3.2. Subscript operator [ ]

3.3.3. Find

3.3.4. Substring

3.3.5. Compare

3.3.6. Concatenate

3.3.7. Insert

3.3.8. Erase

3.3.9. Replace