Chapter 2

 

 

 

Text Box: cout (Outputing Data) // This is a comment. // The computer will ignore lines following two backslashes // Commenting is important when your program is complex. // This will help others follow your code /* To comments a block, start with a backslash and a star, and end with a star followed by a backslash. */ #include <iostream.h> // iostream.h is a file containing code for input/ouput operations main() // Every program must have a main function. /* Don’t worry, in the next unit you’ll learn how to create your OWN function!! */ { cout<<" \t Hello World! \n"; // ‘\t’ is just a tab and ‘\n’ is an endline cout<<"Welcome to Computer Programming."; cout<<endl; // endline cout<<"I hope you have fun this semester!"<<endl; return 0; // Some functions return integers. // You will learn more about this later. }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: Declaring and Initializing #include <iostream.h> main() { int peterpan; /* When you declare an integer (in this case peterpan) the computer will reserve space in memory for it */ int tinkerbell=5; /* tinkerbell is assigned a value of 5. What is on the right is always assigned to what is on the left. */ peterpan=16; /* I didn’t assign a value to peterpan at first, but now I’m assigning it a value of 16. */ cout<<"peterpan: "<<peterpan; cout<<endl; cout<<"tinkerbell: "<<tinkerbell<<endl; return 0; }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: cin (Inputing Data) #include <iostream.h> main() { int simba; cout<<”Insert an integer:“<<endl; cin>>simba; // Computer reads in an integer cout<<simba<<endl; return 0; // The output that follows depends on whatever the user inputs. }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Picture from "Beauty and the Beast" (C) The Walt Disney Co.
 

 

 


Text Box: Different Data Types #include <iostream.h> main() { int belle; float beast; // floats are used for decimals double mrs_pots; /* doubles can store values of much greater magnitude or with greater precision than floats */ belle=4.6; // belle is an integer. /* The computer always truncates decimals if they are assigned to an int. */ beast=4.6; mrs_pots=4.6; cout<<"belle (int): "<<belle<<endl; cout<<"beast (float): "<<beast<<endl; cout<<"mrs_pots (double): "<<mrs_pots<<endl; cout<<endl; return 0; }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: Using Operators #include <iostream.h> main() { int sneezy=2, sleepy=7, happy=12; cout<<sneezy+sleepy<<endl; // 2+7 cout<<sneezy*happy-sleepy<<endl; /* 2 * 12 – 7 Don’t forget your order of operations (multipiclation and division come before addition and subtraction */ // Parentheses are used here to emphasize order of operations: cout<<sneezy*(happy-sleepy)<<endl; // 2 * (12-7) cout<<happy/sneezy<<endl; // 12/2 return 0; }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: Modulus Operator #include <iostream.h> main() { /* The mod operator (%) is associated to the remainder of a certain division. */ int tarzan=10; int t; t=tarzan%5; // The remainder when 10 is divided by 5 is 0 cout<<t<<endl; t=tarzan%4; // The remainder when 10 is divided by 4 is 2 cout<<t<<endl; t=tarzan%3; // The remainder when 10 is divided by 3 is 1 cout<<t<<endl; t=tarzan%7; // The remainder when 10 is divided by 7 is 3 cout<<t<<endl; return 0; }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: Conditional Expressions #include <iostream.h> main() { int snow_white; cout<<"Insert amount of apples: "; cin>>snow_white; cout<<"You have "<<snow_white << (snow_white==1 ? " apple." : " apples.") <<endl; // First operand is a condition (Is there just one apple?) // Second operand is what should print out if condition is TRUE // Third operand is what should print out if condition is FALSE cout<<endl<<"Insert new amount of apples: "; cin>>snow_white; cout<<"Now you have "<<snow_white << (snow_white==1 ? " apple." : " apples.") <<endl; return 0; }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: Characters #include <iostream.h> main() { char robin_hood=’*’; // robin_hood is a character, the * char maid_marian; cout<<"Robin_hood: "<<robin_hood<<endl; cout<<"Insert a character: "; cin>>maid_marian; cout<<"Maid_marian: "<<maid_marian<<endl; /* You can’t have two symbols together and expect the computer to consider it as one single character (In this case I inputed ‘&*’, the and the computer interpreted Maid_marian as ‘&’ only) */ return 0; }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

dumbo18.gif (13062 bytes)
 

 

 


Text Box: if, else if, else #include <iostream.h> main() { float dumbo; cout<<"Insert an integer: "; cin>>dumbo; if (dumbo<50) cout<<"Your number is less than 50"<<endl; else if (dumbo==50) /* Notice how 2 equal signs are used to check if dumbo is equal to 50.*/ cout<<"Your number is 50"<<endl; else /* Don’t make the computer waste time checking using an else if (dumbo>50)*/ cout<<"Your number is greater than 50"<<endl; return 0; /* You can use else if as many times as you want, or you could just have an if followed by an else */ }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: Switch Statements #include <iostream.h> main() { int cruella_de_vil; cout<<"Insert an integer from 1-5: "; cin>>cruella_de_vil; cout<<endl<<endl<<"CRUELLA DE VIL FUN FACT:"<<endl<<endl; switch (cruella_de_vil) /* A switch statement is a convenient way of testing the values of an integers (instead of using a whole bunch of if/else if statements)*/ { case 1: cout<<"Role: comic villain \n"; break; case 2: cout<<"Name derives from the words cruel and devil \n"; break; case 3: cout<<"She loves dalmatians \n"; break; case 4: cout<<"Debut: January 25, 1961 \n"; break; default: // For any other number cout<<"Hobbies: bad driving and wearing fur coats \n"; // You don’t need a break after the last case }; cout<<endl; return 0; }

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Text Box: Increment and Decrement Operators #include <iostream.h> main() { //This concept will be very important when using loops (next 3 programs) int jiminy, cricket, fairy; jiminy=10; cout<<"Initial value of jiminy: "<<jiminy<<endl; cout<<"jiminy++: "<<jiminy++<<endl; /* Print 10 and then postincrement jiminy */ cout<<"Final value of jiminy: "<<jiminy<<endl<<endl; cricket=15; cout<<"Initial value of cricket: "<<cricket<<endl; cout<<"++cricket: "<<++cricket<<endl; /* Preincrement cricket and then print 16 */ cout<<"Final value of cricket: "<<cricket<<endl<<endl; fairy=4; cout<<"Initial value of fairy: "<<fairy<<endl; fairy-=2; /* This is essentially the same thing as reassigning fairy: fairy=fairy-2 */ cout<<fairy<<endl<<endl; fairy=4; fairy=fairy-2; // Reassignment of fairy cout<<fairy<<endl<<endl; return 0; }