Lesson1.md

Lesson 1: Basic Operations, Types, and Conditional Statements

Basic Operations

1. Assignment

   Assignment is how we store stuff. It's kind of like x in algebra:

   x = 5
   greeting = "Greetings and salutations!"
   x = greeting

2. Math

   Oh no! This is another math class, isn't it? NO! But we still use it!

   value1 = 5
   value2 = 10
   value3 = value1 + value2
   
   message1 = "'Sup?"
   message2 = message1 * value3

   The * (asterisk) acts as our multiplicaiton symbol. We can't use an x because the computer reserves x for us to define ourselves.

   • Multiplicaiton: *
   • Division: /
   • Addition: +
   • Subtraction: -
   • Modulo: %

Types

1. Integers

   Ever had trouble classifying numbers? HA. Programming will fix you.

   x = 0        # Yes, zero is an integer
   x = 1        # Yes, one is an integer
   x = int(3.5) # x stores a 3 here
   x = int('4') # x stores a 4 here

2. Floating-point numbers

   You remember these from Saxon, don't you? Well, you shouldn't! Programmers call rational numbers floating-poing numbers or floats for short. Basically everybody else uses different terminology. Just remember that no matter what, floats have a decimal point

   x = 1.0
   x = float('4.5')
   x = 12345.000121212

   Python has a quirky way of dealing with division that should be mentioned here.

   x = 1 / 3        # x is 0
   x = 2 / 3        # x is still 0
   x = 99 / 100     # x is STILL 0
   x = 100 / 100    # x is one
   x = float(1/3)   # x is 0.0
   x = float(1) / 3 # x is 0.3333333333333333

   That's called truncation, by the way.

3. Strings

   You definitely shouldn't remember strings from Saxon. Strings are the little guys surrounded by quotation marks.

   x = 'Hi'                       # x is a string
   x = "Bye"                      # x is a string
   x = """What's up with this?""" # x is a string
   x = '5'                        # x is a string
   x = str(5)                     # x is a string
   x = str('5')                   # x is a string
   x = Hi                         # NameError

Conditional Statements

Conditional statements in Python are handled by the if keyword.

x = 5 # Assigns 5 to x

if x is 5: # "if x is equal to 5"
    print "x is 5"

if x == 5: # "if x is equal to 5"
    print "x is 5"

# Notice the `==` symbol. Remember that `==` is not the
# same as `=`. Here are some other conditional statements:

x = 6.0

if x > 5: # "If x is greather than 5"
    print "x is not equal to 5"
elif x < 5: # "Else if x is less than 5"
    print "x is less than 5"
else:
   print "x equals 5"

if x >= 6: # "If x is greater than OR equal to 6"
    print "x is greater than or equal to 6"

if x > 6 or x == 6:
    print "x is greater than or equal to 5"