1. COSC 235: Programming and Problem Solving Ch. 2: Your first programs!!! Instructor: Dr. X

2. Goals Understand Input Process Output (IPO) Use variables Understand expressions Use and understand iteration 2

3. Software Development Process Analyze Problem – what? Determine Specs - IO Create Design – how? Implement – make it Test/Debug – break it Maintain - …

4. Software Development Process https://opensw.files.wordpress.com/2009/07/software_development1.jpg

5. Program Elements Names Expressions Input/Output

6. Names Make them meaningful (descriptive) Camel case Use _ to connect two words Beware! – Symbols – Keywords – Case sensitive

7. Expressions Calculate new values Evaluate right hand side Assign to left! Spaces: are they important?

8. Output first… because it is easier Syntax print(,, …, ) print() Semantics: display information (data)

9. Input is a little tougher… Syntax = input( ) = eval(input( )) Semantics?

10. Assignment Syntax = Semantics? Have we seen this before?

11. Simultaneous assignment Syntax,, …, =,, …, Exercise: Write a sequence of assignment statements that exchange the values of thing1 & thing2 http://www.cliparthut.com/thing-1-and-2-dr-seuss-clipart-UnZOY3.html

12. Exercise Print “Hello world” 10 times, then print it 100 times… Print the integer numbers from 0..10, 0..100

13. Loops https://upload.wikimedia. org/wikipedia/commons/ thumb/f/f4/Shockwave_c oaster_sfot.jpg/220px- Shockwave_coaster_sfot.j pg http://3.bp.blogspot.com/- eYwYLrlLWZs/UNlpG3goYgI/AAAA AAAACaI/MdQ2- CPcJYY/s1600/01.gif http://img1.wikia.noc ookie.net/__cb20110 112235951/logopedi a/images/0/0a/Froot _Loops_logo.jpg

14. Loops Syntax for in : Semantics: avoid doing repetitive things using copy paste =) OR execute a definite sequence of steps

15. References “Python Programming: An Introduction to Computer Science”, 2 nd ed., John M. Zelle