Python - Programming Language
This course covers the basics of programming in Python. Work your way through the videos and we'll teach you everything you need to know to start your programming journey!

In One Video

Lesson 36
Author : Mike Dane
Last Updated : October, 2017


Python Overview

Python is a general purpose, dynamically typed and interpreted, object oriented programming language that was created in the late 1980s by Guido van Rossum.

Python’s design philosophy revolves around readability. It’s meant to be easy to read and easy to write. This is accomplished by using white-space to deliniate code blocks instead of the more traditional curly brackets and semi-colons.

How Python Runs

Generally all python code is run using an interpreter. The most popular and original interpreter is called CPython, because it’s implemented in the c programming language. Several other interpreters exist however, many of which are implemented in languages other than C like Java and C#.

The most common Python interpreter CPython, uses an automatic garbage collector to manage memory. And Python is widely known for having a non-traditional, minimalist syntax which is largly based on white space, and designed to be clean and readable.

Python Versions

When first getting into python it can be a bit confusing becasue unlike many other programming languages Python has two major, non-compatible versions that are currently widely used.

Python version 2.7.3, released in 2012, is the last iteration of verison 2 that was released. This verison is for the most part, backwards compatiable with all previous versions.

In 2008, the Founder, Guido van Rossum decided to clean up the Python codebase and overhall a lot of the things in Python 2 that he didn’t like, thus creating Python 3.

Python 3 was adopted slowly at first, mainly because it is not backwards compatible with Python 2, and there was a huge eco-system of package libraries written for Python 2 which now would not work in python 3.

But now-a-day’s the Python 3 ecosystem has for the most part caught up, making Python 3 the obvious choice for new developers looking to learn the language. Python 3 is also the version that will be taught in this tutorial.

Choosing an IDE

Many developers choose to write Python using a specilized integrated development enviornment. Three of the most popular are Eclipse, PyCharm and Netbeans.

Code

Printing

Copyprint("Hello")
print("World")      
print("!")

Variables and Data Types

Copy'''
Names are case-sensitive and may begin with:
   letters, $, _
After, may include
   letters, numbers, $, _
Convention says
   Start with a lowercase word, then additional words are separated
   by underscores
   ex. my_first_variable
'''
name = "Mike"    # Strings
age = 30         # Integer
gpa = 3.5         # Decimal
is_tall = True    # Boolean -> True/False

name = "John"

print("Your name is " + name)
print("Your name is", name)

Casting and Converting

Copyprint( int(3.14) )
print( float(3) )
print( str(True) )
print( int("50") + int("70") )

Strings

Copygreeting = "Hello"
#indexes:   01234

print( len(greeting) )
print( greeting[0] )
print( greeting[-1] )
print( greeting.find("llo") )
print( greeting.find("z") )
print( greeting[2:] )
print( greeting[2:3] )

Numbers

Copyprint( 2 * 3 )       # Basic Arithmetic: +, -, /, *
print( 2**3 )       # Basic Arithmetic: +, -, /, *
print( 10 % 3 )      # Modulus Op. : returns remainder of 10/3
print( 1 + 2 * 3 )   # order of operations
print(10 / 3.0)      # int's and doubles


num = 10
num += 100 # +=, -=, /=, *=
print(num)

++num
print(num)

# Math module has useful math methods
import math
print( pow(2, 3) )
print( math.sqrt(144) )
print( round(2.7) )

User Input

Copyname = input("Enter your name: ")
print("Hello", name + "!")

num1 = int(input("Enter First Num: "))
num2 = int(input("Enter Second Num: "))
print(num1 + num2)

Lists

Copylucky_numbers = [4, 8, "fifteen", 16, 23, 42.0]
#       indexes  0  1       2      3   4   5

lucky_numbers[0] = 90
print(lucky_numbers[0])
print(lucky_numbers[1])
print(lucky_numbers[-1])
print(lucky_numbers[2:])
print(lucky_numbers[2:4])
print(len(lucky_numbers))

2 Dimensional Lists

CopynumberGrid = [ [1, 2], [3, 4] ]
numberGrid[0][1] = 99

print(numberGrid[0][0])
print(numberGrid[0][1])

List Functions

Copyfriends = []
friends.append("Oscar")
friends.append("Angela")
friends.insert(1, "Kevin")

# friends.remove("Kevin")
print( friends )
print( friends.index("Oscar") )
print( friends.count("Angela") )
friends.sort()
print( friends )
friends.clear()
print( friends )

Tuples

Copylucky_numbers = (4, 8, "fifteen", 16, 23, 42.0)
#       indexes  0  1       2      3   4   5

lucky_numbers[0] = 90
print(lucky_numbers[0])
print(lucky_numbers[1])
print(lucky_numbers[-1])
print(lucky_numbers[2:])
print(lucky_numbers[2:4])
print(len(lucky_numbers))

Functions

Copydef add_numbers(num1, num2=99):
     return num1 + num2

sum = add_numbers(4, 3)
print(sum)

If Statements

Copyis_student = False
is_smart = False

if is_student and is_smart:
	print("You are a student")
elif is_student and not(is_smart):
	print("You are not a smart student")
else:
	print("You are not a student and not smart")


# >, <, >=, <=, !=, ==
if 1 > 3:
	print("number omparison was true")


if "dog" == "cat":
   print("string omparison was true")

Dictionaries

Copytest_grades = {
    "Andy" : "B+",
    "Stanley" : "C",
    "Ryan" : "A",
    3 : 95.2
}
print( test_grades["Andy"] )
print( test_grades.get("Ryan", "No Student Found") )
print( test_grades[3] )

While Loops

Copyindex = 1
while index <= 5:
	print(index)
	index += 1

For Loops

Copyfor index in range(5):
    print(index)

lucky_nums = [4, 8, 15, 16, 23, 42]
for lucky_num in lucky_nums:
    print(lucky_num)

for letter in "Giraffe":
    print(letter)

Exception Catching

Copytry:
    answer = 10 / int(input("Enter Number: "))
except ZeroDivisionError as e:
    print(e)
except:
    print("Caught any exception")       

Classes and Objects

Copyclass Book:
    def __init__(self, title, author):
        self.title = title
        self.author = author

    def read_book(self):
         print("Reading", self.title, "by", self.author)

book1 = Book("Harry Potter", "JK Rowling");
# book1.title = "Half-Blood Prince"

print(book1.title)
book1.read_book()

Getters and Setters

Copyclass Book:
    def __init__(self, title, author):
        self.title = title;
        self.author = author

    @property
    def title(self):
        print("getting title")
        return self._title

    @title.setter
    def title(self, value):
        print("setting title")
        self._title = value

    @title.deleter
    def title(self):
        del self._title


    def read_book(self):
         print("Reading", self.title, "by", self.author)

book1 = Book("Harry Potter", "JK Rowling");
# book1.title = "Half-Blood Prince"

print(book1.title)
book1.read_book()

Inheritance

Copyclass Chef:

   def __init__(self, name, age):
       self.name = name
       self.age = age


   def make_chicken(self):
       print("The chef makes chicken")

   def make_salad(self):
       print("The chef makes salad")

   def make_special_dish(self):
       print("The chef makes bbq ribs")

class ItalianChef(Chef):

   def __init__(self, name, age, countryOfOrigin):
       self.countryOfOrigin = countryOfOrigin
       super().__init__(name, age)

   def make_pasta(self):
       print("The chef makes pasta")

   def make_special_dish(self):
       print("The chef makes chicken parm")


myChef = Chef("Gordon Ramsay", 50)
myChef.make_chicken()

myItalianChef = ItalianChef("Massimo Bottura", 55, "Italy")
myItalianChef.make_chicken()
print(myItalianChef.age);