Introduction to Programming Concepts (for True Beginners!)

Thanks to our sponsor:

Thanks to our sponsor:

Class notes

A few quick announcements

Upcoming Events

Introduction to Javascript & jQuery

Saturday, July 26, 2014

Simple Energy

Welcome!

Girl Develop It is here to provide affordable and accessible programs to learn software through mentorship and hands-on instruction.

Some "rules"

  • We are here for you!
  • Every question is important
  • Help each other
  • Have fun

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
  • 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
  • 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!';
  • 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:
  1. Possible languages to use:
    • Python: computer program
    • SQL: manage the data
    • HTML/CSS: web development to share on the Internet
  2. Programming structures:
    • 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