Introduction to Programming Concepts (for True Beginners!)

Introduction to Programming Concepts (for True Beginners!)

Thanks to our sponsor:

Thanks to our sponsor:

Class notes

• Class slides (streamlined): http://gdiboulder.github.io/gdi-boulder-intro-programming-concepts/

A few quick announcements

Upcoming Events

Introduction to Javascript & jQuery

Saturday, July 26, 2014

Simple Energy

Welcome!

Your instructors

• Teri Charles
• Jen Skiendzielewski

Computer Programs

• Computer programs are everywhere.
  • Run parts of your car.
  • Let you check your email.
  • Underlie that favorite app on your smartphone.
• But what are they, really?

What is a Computer Program?

• At its core, a computer program is a way of getting something done.

Programming Languages

• A programming language is basically a set of strings (letters, numbers, commands) that is changed into machine code that the computer can understand.

Programming Languages

• To develop websites, you might use HTML, JavaScript, Python, Java, PHP.
• To create databases and move information in and out of them, you might use MySQL, SQL, Dbase.
• To write applications like Microsoft Word or Adobe Acrobat, you might use C++, Java, Visual Basic

Important to Remember

• One of the most important things to remember is that when programming, you are doing something for people, and that the computer and the program mediate that. ~Michael Bolton (Software Tester extraordinaire)

Computers are dumb

• Computers can only do what they have instructions for-- and they take those instructions VERY literally.

Demonstration

Memory

• A computer doesn’t have a memory like we do. Sure, a computer has “memory”-- In fact it has a couple of kinds...

Kinds of Memory - ROM

• ROM or Read-only memory is the more permanent kind.

Kinds of Memory - Storage

• More permanent, more long term memory.

Kinds of Memory - RAM

• RAM or Random-access memory is less permanent.

Programming structures

• No matter what programming language you use, the structures that are available are fairly similar.
  • Variables
  • Logical structures:
    • If/Else statements
    • Loops

Variables

• A variable is essentially a storage container for information.
• Examples:
  • age = 28
  • color = blue
• There are different kinds of variables based on the information that you want to store.

Integer Variables

• Integer variables are used to store positive or negative whole numbers.

String Variables

• String variables are used to store text.

Numbers as strings

• You can store a number as a string variable.
• If you store a number as a string variable, you can’t use it in any math calculations.

Boolean Variables

• Boolean variables are used to store the value TRUE or FALSE (yes or no).

Logical structures

• Now that you can store data, you probably want to do something with it.

Operators

• Operators are words or symbols that let you compare, combine, or evaulate something to produce an output.
• A few xamples:
  • = (equal to)
  • > (greater than)
  • < (less than)
  • >= (greater than or equal to)
  • < = (less than or equal to)
  • != (not equal)
  • and
  • or

If/Then/Else

• If/Then/Else statements evaluate a condition and take actions based on the result.

Let's Do Some If/Then/Else! (1/4)

If/Then/Else Excercises (2/4)

• For this excercise, we're using Ruby.
• Go to repl.it, which is an online terminal to practice writing code.
• Choose 'Ruby'.

IF Excercise (3/4)

cart_total = 8

if cart_total > 2
    print "You get free shipping!"
end
				="html">

• Change the numbers to see what happens.
• Change the operators (greater than, less than, etc.)

IF/THEN/ELSE Excercise (4/4)

cart_total = 8

if cart_total > 2
    print "You get free shipping!"
else
    print "You'll have to pay for shipping."
end
				="html">

• Change the numbers to see what happens.
• Change the operators (greater than, less than, etc.)
• Change the string statements.

Loops

• A loop is a list of instructions that repeats until a certain condition is reached.

Let's Do Some Loops! (1/4)

Loop Excercise (2/4)

• For this excercise, we're using Python.
• Go to repl.it, which is an online terminal to practice writing code.
• Choose 'Python'.

Loop (while) Excercise (3/4)

papers_to_deliver = 65

while papers_to_deliver > 0:
    print papers_to_deliver
    papers_to_deliver = papers_to_deliver - 1
print 'Out of papers! Go home!';
				="html">

• Change the numbers to see what happens.
• Change the operators (greater than, less than, etc.)
• Change the string statements.
• See the next slide that will explain what is happening in the loop (via a diagram).

Beware the Infinite Loop!

• An infinite loop is a loop that will never meet the condition to stop. It will keep going until it's used up all your computer's (or server's) memory (RAM). This is bad!
• Example: In the While loop:
  • If the "papers_to_deliver = papers_to_deliver - 1" line was missing, it would keep looping because 65 is always greater than 0!
  • If "papers_to_deliver = papers_to_deliver - 1" was changed to "+ 1", it would keep adding 1 to 65 forever!

Project Implementation Example

• When companies implement a new program, they take various things into consideration:

• Python: computer program
• SQL: manage the data
• HTML/CSS: web development to share on the Internet

• Variables: place to store the information such as, colors, amounts, etc.
• Detailed steps to tell the computer what to do.
• Loops: Instructions that keeps repeating as neccessary.

Coding Classes Resources (most are free) and Books

• Code year:www.codecademy.com/tracks/code-year
• Codecademy: www.codecademy.com
• Coursera: www.coursera.org
• Kahn Academy: www.khanacademy.org
• Skillcrush: www.skillcrush.com
• Udacity: www.udacity.com
• Udemy: www.udemy.com
• And of course, GDIBoulder!
• Learn to Program, by Chris Pine
• Everyday Scripting in Ruby, by Brian Marick