ACM Init() lesson 1
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This document summarizes an introductory computer science class that teaches Ruby programming. It introduces the course, resources, instructors, and covers data types, variables, math operations, string methods, printing to the screen, comments, and naming conventions. The class assumes no prior experience and aims to teach programming fundamentals in Ruby, an easy-to-learn and widely used language.
ACM Init() lesson 1
- 1. ACM init() Day 1: October 23, 2014
- 2. Kelly
- 3. Akshay
- 4. Daniel
- 5. Welcome! Welcome to ACM init(), a Computer Science class for beginners. Over the course of the next few weeks, you will be learning Ruby, a flexible, widely used programming language.
- 6. About the Course • This course assumes no prior programming experience • Hosted by the Association for Computing Machinery (ACM) • This course will be teaching you how to code in a language called Ruby • NO EXAMS!!!!
- 8. Resources for You Our website: acm.cs.ucla.edu Slides: slideshare.net/uclaacm Facebook: https://www.facebook.com/groups/717821374976381/ Want to contact us? Kelly: [email protected] Daniel: [email protected] Akshay: [email protected]
- 9. Remember: If you have any questions, ask! Chances are someone else has the same question and is hesitant to ask.
- 10. If you don’t understand something, it is more important that you learn it than we finish everything today.
- 11. Why Computer Science? • Computer Science is a fast growing field with a surplus of high-paying jobs • Learning a programming language will enhance your resume and make you more desirable to companies • Furthermore, learning how to code will better your problem-solving skills and help you in all of your classes Source: http://www.ovrdrv.com/blog/making-computer-science-cool/
- 12. The numbers speak for themselves... Source: http://code.org/promote
- 13. Who knows what a programming language is?
- 14. Why Learn Ruby? • Ruby is easy to read and use, and is considered to be one of the best first languages to learn • Ruby developers are in high demand • Ruby is useful -- Ruby on Rails is one of the most popular web programming platforms in the startup community
- 16. Computing the Factorial of a Number • Factorial: written as #! • For example, 5! is 5*4*3*2*1 = 120 • I wrote a simple program called fact.rb that will compute the factorial for us • Let's try it out! Compute the factorial of 6. • ruby fact.rb 6
- 18. A Bit About Computers Computers think in 0s and 1s. Everything that you input into a computer gets stored in this manner. For example: You don't need to know how this conversion works. However, the concept is important because it is the reason why we need programming languages. Human-readable programming languages go through a process that converts them to binary, which can be understood by the compter.
- 19. How do we make our code work? Ruby is what is called an interpreted language. That means that the computer runs one line of code at a time. We can't just type code into a word document and hope it will magically do something. We need an interpreter that will help the computer understand our code.
- 20. koding.com koding.com is an easy way to run code that requires no downloading or storage space.
- 21. Enter your email and choose a username
- 22. This is what you should see once you log in.
- 23. Let's learn how to run a program. Type puts "I love computers!" into the top window in Koding.
- 24. Now, save the file. Select the option Save As.
- 25. Select a directory to save the file in. I choose a directory I created called ACMclass. Now, name the file myfirstfile.rb
- 26. Press Save
- 27. The file has been saved! Now, let's run it.
- 28. First, we need to make sure we are in the right directory. Type in cd 'theDirectoryYouSavedIn' then press Enter. It changed!
- 29. Now we can access our file! Time to run it. Type in ruby myfirstfile.rb This tells Koding that we are about to run a Ruby file.
- 30. Press Enter, and it runs! The screen printed out "I love computers!"
- 31. Time to start learning Ruby.
- 32. Data Types • Why? Say "five". Did you say 5 or five? • There are three main data types in Ruby: numbers, booleans, and strings. • Numbers: Exactly what it sounds like. (example: 1, 400, 45.7) • Booleans: Something that is either true or false. • String: A word or phrase. (example: "Hello World!")
- 33. Variables We can store these data types in variables so we can come back and use them again later. Take a look: Now if we want to use any of these stored values again all we have to do is type the variable name!
- 34. Math There are six main math operations we are going to go over today.
- 35. + - * / • + is addition • - is subtraction • * is multiplication • / is division • These work the same way your calculator does -- no surprises here
- 36. ** and % • ** (exponent) raises one number to the power of another. For example, 2**3 would be 8 because 2*2*2=8 • % (modulus) returns the remainder of division. For example, 25%7 would be 4 because 25/7 is 3r4.
- 37. Printing to the Screen There are two main commands that will allow you to print text out to the screen. These commands are 'puts' and 'print'.
- 38. 'puts' vs 'print' The 'print' command just takes whatever you give it and prints it to the screen. 'puts' (for "put string") is slightly different: it adds a new (blank) line after the thing you want it to print.
- 39. 'puts' vs. 'print' example
- 40. String Methods • Remember, a string is is word or a phrase. Ruby provides several methods for us to make it easier to use strings • '.length' : finds the length of the string • '.reverse' : reverses the string • '.upcase' : changes all letters to uppercase • '.downcase' : changes all letters to lowercase
- 42. We've covered all the Ruby syntax we're going over for today. Now, let's learn a bit about writing good code.
- 43. Comments What if you write a really long program then not look at it for a year? What if you're working on a project with other people and you have to share your code? We need a way to explain what is going on in the programs we write. The solution? Comments.
- 44. How to add comments Comments are a tool we have to communicate what our code is intended to do. To put a comment in your code all you have to do is type # your comment here Anything that comes after '#' and is on the same line will be ignored when the code is being run.
- 45. Comment Example
- 46. Naming Conventions • Remember that we can give values to variables so we can use the same value again later • We can name these variables whatever we want • Doesn't it make sense to give variables descriptive names? • Some naming rules: • Separate words with underscores '_' • Do not start a variable name with a number, symbol, or uppercase letter • The variable name should describe what the variable contains or will be used for
- 47. Naming Examples
- 48. What we covered • A little bit about Ruby • How to use Koding • Data types: numbers, string, and booleans • Variables • Math • How to print to the screen • String methods • How to write good code
- 49. Any questions? Office Hours will be right after the class every time.