C++ Programming Basics Chapter 1 Lecture CSIS 10A

1. C++ Programming BasicsChapter 1 LectureCSIS 10A

2. Agenda • Hardware Basics  • The IDE • My First Program • Its all G(r)eek to me • Variables and Declarations • Input and Output

3. ALU Control Input Mouse Keyboard Scanner Hard Disk Floppy Disk Monitor Printer Speakers Memory Output Anatomy of a Computer

4. The CPU uses machine language Assembly instructions to calculate the radius of a circle: LOAD radius LOAD pi MULTIPLY LOAD two MULTIPLY STORE circle

5. Compilers to the Rescue ! High level languages like C++ allows writing code that is easier to understand and universally works on any CPU. circle=2.0*radius*pi; The compiler is what translates instructions from C++ into Machine language.

6. Agenda • Hardware Basics • The IDE  • My First Program • Its all G(r)eek to me • Variables and Declarations • Input and Output

7. THE MECHANICS OF WRITING A PROGRAM • Editing -- Writing a program • Compiling -- Translating from C++ into machine language • Linking -- Combining your program with other libraries • Running – Letting the computer execute a program • Debugging – Running step by step through a program searching for mistakes The Integrated Development Environment (IDE) combines 1-5.

8. Agenda • Hardware Basics • The IDE • My First Program  • Its all G(r)eek to me • Variables and Declarations • Input and Output

9. Hello World ! • Lets start off the traditional way • Program that prints out “Hello World” on your output console (your screen) • Lets start off on our journey…..

10. Steps • Create new source file • Write the code • Create a workspace (only in MSVC++) • Compile • Link • Execute

11. Agenda • Hardware Basics • The IDE • My First Program • Its all G(r)eek to me  • Variables and Declarations • Input and Output

12. It’s all G(r)eek to me • … actually, its C++ • Lets dissect and analyze a simple program

13. 20,000 ft. above sea level #include <iostream> using namespace std; int main() { // This is my first program cout << "Hello World" << endl; system("pause"); return 0; }

14. 20,000 leagues under the sea #include <iostream> • Actually includes some information into your code • Contains some definitions that are needed for your code • More of this later on in the course

15. 22,000 leagues under the sea using namespace std; • This line refers to a set of standard object name definitions • For now, this is “boilerplate”—stick it in cause it makes everything work!!

16. … deeper…. • int main() • This is the piece of code (function) that is operated on first when a program is executed • What’s a function ??? • …. all that’s coming soon …

17. … even deeper…. • //This is my first program • This is a comment you write to yourself • Useful when writing large programs • Starts with a //

18. … and deeper….. • Output operator cout << “Hi”<<endl; • cout is the console monitor (your display) • << is the output operator. Use to chain together your output message. • “Hi”is a string literal • endl means end-line (like enter key)

19. … getting sleepy?….. • For the Bloodshed environment…Hold the display open so you can read it (pressing a key will continue) system("pause"); • Finish up this program, return a 0 to operating system (everything ended OK) return 0;

20. … and even deeper …. • {} delineates the code block • Each line ends with a ;

21. Other types of cout statement cout<< “ my age is” <<endl << 39<<endl; cout<< “ my age is 39”; cout<< “ what’s your’s”; Escape with \ Output a “ cout<<“ \” ” <<endl; Output a endl cout<<“\n”;

22. Tom’s All Purpose Program Shell #include <iostream> using namespace std; int main() { // Your code here ... system("pause"); return 0; } • Future slides may neglect some of the above components for clarity

23. You Do It • Modify your hello world program to print your name, address and phone number (COULD BE FAKE!) on three lines: Tom Rebold 1600 Pennsylvania Ave 123-456-7890 Experiment with line breaks

24. Lets get moving….. • We’ll learn as we proceed • You’ll be saying “Aha!” or “Oho!” when you hear these terms again • Let’s play around a bit more

25. What more ? • Variables and Declarations • Getting User Input

26. Variables and Declarations • Variables represent storage locations in the computer’s memory variable = expression • Assignment is from right to left n = 5; • Would give n the value 5

27. Using int Variables int main() { int m,n; m = 44; cout << “m = “ << m; n = m + 33; cout << “ and n = “ << n << endl; }

28. m int Clearing the haze int m; m = 44.0; 44

29. m 44 int n int Clearing the haze int m = 44, n; n = m + 33; 44 + 33 = 77 77

30. Want more ? • Variables and Declarations • Getting User Input

31. User Input with cin • How shall I feed in data ? • Remember cout ? • Meet cin cin >> m; • Will put the value entered through the console (keyboard) into m

32. User Input with cin int main() { cout << "Enter the value of m:"; cin >> m; cout << "m = " << m << endl; }

33. User Input with cin int main() { cout << “Enter the value of m:”; cin >> m; cout << “m = “ << m << endl; } HEY THERE’S SOMETHING WRONG HERE !!!

34. User Input with cin int main() { int m; cout << "Enter the value of m:"; cin >> m; cout << "m = " << m << endl; }

35. Your turn () • from hello.cpp File>SaveAs age.cpp • Delete all the cout statements. Add lines to: a) Declare a variable called age b) Display a message asking for data (such as “tell me your age”)c) read the data into age d) display the variable age with a descriptive message. (refer to slide 34)

36. That’s a wrap ! • What we learned so far: • How to write a basic C++ program • The structure of a program • Displaying to the console (cout) • Variables • Getting user input via the console (cin)