1. CS114-009 Class 03 Topics  Sequence statements Input Output Assignment  Expressions Read pages Read pages 40 – 49 for next time

2. Sequence Statements statement; Sequence statements statement; No decisions Just perform one statement after another

3. Sequence Statements Can write entire programs just using sequence statements Basics Sequence statements  Input  Output  Assignment (computation) #include using namespace std; int main ( ) { declaration (s); stmt 1; stmt 2; stmt 3; … stmt N; }

4. Input and Output >> << Arrows indicate direction that the data flows >> data flows from the input device (user) into a variable <<data flows from the program to the output device (screen)

5. Input statements Standard input is cin Send item from input to a variable via the >> operator  Can send one at a time  Can sent lots at once  System skips “white space” to find variable  White space is: tabs, spaces, new- lines 13 5 27 U a 7 int a, b, c; cin >> a >> b; cin >> a >> c; cin >> b; char a, b, c; cin >> c; cin >> b >> a;

6. Output statements Note the “double” Note the “=“ Standard output is cout Send item to output via << operator  Can send one at a time  Can send lots at once  endl means end of line  Can send special characters (see book for details) int a=5, b=10, c, d; double x=3.14, y=2.718; cout << a << b << endl; cout << a << “ “<< b << endl; cout << x; cout << y << endl; cout << endl << a << endl; cout << ‘\t’ << a << endl; cout << c << “ ? “ << endl;

7. Class Exercises Write a C++ program that reads in five integer values, storing them in five variables, and then prints them out in the opposite order that you entered them.  Write it using five separate input statements and five separate output statements.  Write it using one input statement (multiple >> operators) and one output statement (multiple << operators). Repeat the exercise for five “char” variables.

8. Assignment statements Comments  Assignment operator is =  Operands include + and – * and / % (mod operator) think “remainder” from third grade division  20 / 6 = 3 remainder 2  20 % 6 = 2 int a=5, b=10, c=2, d, e, f; d = a * 2 + (c – 3); e = b / c; e = e + 1; f = (a % c) + b;

9. Basic Data Types (variables) We focus on int, double and char  Use these more than any other types in CS 114 Integers (int)  Can store numbers from +/- 2 billion (roughly)  Occupies 4 bytes (32 bits) Real numbers (double)  store an approximation (exponent and mantissa)  Occupies 8 bytes (64 bits) Actual internal bit representation for 2 (int) and 2.0 (double) are completely different

10. Assignment and Variables C++ does arithmetic based on the type of the operands  Integer arithmetic is much faster than real (double) arithmetic  Impacts division 5/ 2 = 2 (integers only) 5./ 2. = 2.5 (real numbers) int a=5, b=10, c=2, d, e, f; d = a * 2 + (c – 3); e = b / c; e = e + 1; f = (a % c) + b; double x; x = 2 / 5;

11. Converting numbers When dealing with numbers double num; num = 1.0 / 3.0; num = 1.0 / 3; num = 1. / 3; Tell compiler to convert this value to a double  “casting” num = double (1) / double (3); num = double (1) / 3; num = 1 / double (3); Integer to character  A char is an ASCII value in the range of 1 to 255  Chars are “small” ints char int double

12. Class Exercise What are the final values for e, f, g, and y? #include using namespace std; int main( ) { int a=2, b=4, c=8, d=5, e, f, g; double x = 2.5, y; e = (a + b * c) / (d + 12); f = x / 2; g = c % d; y = c / d + x; }

13. Code a program in.NET Steps involved  Invoke Microsoft’s Visual Studio.NET 2005  Create an “empty project” for this program Save this project on your own home disk (“L:” drive).  We’ll use this same code on Wednesday.  Enter the C++ code  Run the program  Save this program

14. Homework #2 Due: e-mail your.cpp file to vrbsky@cs.ua.edu Tues. 9/2 before class vrbsky@cs.ua.edu  Run the program using the instructions at the link below  Print an additional line after hello that says goodbye http://cs.ua.edu/~vrbsky/CS114/Instr.NET.htm

15. Info for.NET 2005 Before we start next exercise, some hints about using.NET 2005 You must create/save a project on the L: drive to use for the class exercises You only need to create/save one project Use this project for all of the programs you write for class exercises

16. When Creating Your Project… In location, type L: L:\ represents your file space on COE It is important to save your files to L:\ as the lab machines are wiped clean on a daily basis.

17. Info for.NET 2005 For each class exercise can create a new.cpp file Save this new.cpp and add as an existing file to your project However, you can only have one.cpp file with a “main ()” in it Must delete the previous.cpp  Right click on file name to remove, select remove option  file will still exist on your :L drive, just not in the project Source folder (you must add it if you want to run it again)

18. End of Class 03 Read pages 40 – 49 for next class.