Notes

Basics

def foo():
    """
    The foo function does many amazing things that you
    should not question. Just accept that it exists and
    use it with caution.
    """
    secretThing()

Numbers

# Using Float
print(17)               # => 17
print(float(17))        # => 17.0

# Using Int
print(17.0)             # => 17.0
print(int(17.0))        # => 17

# Using Str
print(str(17.0) + ' and ' + str(17))        # => 17.0 and 17

Strings

print('''My instructions are very long so to make them
more readable in the code I am putting them on
more than one line. I can even include "quotes"
of any kind because they won't get confused with
the end of the string!''')
# Shortcut to get from the beginning of a string to a certain index.
print("Spaghetti"[:4])  # => Spag
print("Spaghetti"[:-1])    # => Spaghett

# Shortcut to get from a certain index to the end of a string.
print("Spaghetti"[1:])  # => paghetti
print("Spaghetti"[-4:])    # => etti
print("Spaghetti".index("h"))    # => 4
print("Spaghetti".index("t"))    # => 6
print("Spaghetti".count("h"))    # => 1
print("Spaghetti".count("t"))    # => 2
print("Spaghetti".count("s"))    # => 0
print('''We choose to go to the moon in this decade and do the other things,
not because they are easy, but because they are hard, because that goal will
serve to organize and measure the best of our energies and skills, because that
challenge is one that we are willing to accept, one we are unwilling to
postpone, and one which we intend to win, and the others, too.
'''.count('the '))                # => 4
first_name = "Billy"
last_name = "Bob"
print('Your name is {0} {1}'.format(first_name, last_name))  # => Your name is Billy Bob

Variables and Expressions

a = 7
b = 'Marbles'
print(a)         # => 7
print(b)         # => Marbles
count = max = min = 0
print(count)           # => 0
print(max)             # => 0
print(min)             # => 0
a = 17
print(a)         # => 17
a = 'seventeen'
print(a)         # => seventeen

Boolean Data Type

# Logical AND
print(True and True)    # => True
print(True and False)   # => False
print(False and False)  # => False

# Logical OR
print(True or True)     # => True
print(True or False)    # => True
print(False or False)   # => False

# Logical NOT
print(not True)             # => False
print(not False and True)   # => True
print(not True or False)    # => False

Comparison Operators

Identity vs Equality

print (2 == '2')    # => False
print (2 is '2')    # => False

print ("2" == '2')    # => True
print ("2" is '2')    # => True

# There is a distinction between the number types.
print (2 == 2.0)    # => True
print (2 is 2.0)    # => False

If Statements

if name == 'Monica':
    print('Hi, Monica.')
if name == 'Monica':
    print('Hi, Monica.')
else:
    print('Hello, stranger.')
if name == 'Monica':
    print('Hi, Monica.')
elif age < 12:
    print('You are not Monica, kiddo.')
elif age > 2000:
   print('Unlike you, Monica is not an undead, immortal vampire.')
elif age > 100:
   print('You are not Monica, grannie.')

While Statements

spam = 0
while spam < 5:
  print('Hello, world.')
  spam = spam + 1
spam = 0
while True:
  print('Hello, world.')
  spam = spam + 1
  if spam >= 5:
    break
spam = 0
while True:
  print('Hello, world.')
  spam = spam + 1
  if spam < 5:
    continue
  break

Try/Except Statements

a = 321
try:
    print(len(a))
except:
    print('Silently handle error here')

    # Optionally include a correction to the issue
    a = str(a)
    print(len(a)
a = '321'
try:
    print(len(a))
except:
    print('Silently handle error here')

    # Optionally include a correction to the issue
    a = str(a)
    print(len(a))
a = 100
b = 0
try:
    c = a / b
except ZeroDivisionError:
    c = None
print(c)
a = 100
b = 0
try:
    print(a / b)
except ZeroDivisionError:
    pass
a = 100
# b = "5"
try:
    print(a / b)
except ZeroDivisionError:
    pass
except (TypeError, NameError):
    print("ERROR!")
# tuple of file names
files = ('one.txt', 'two.txt', 'three.txt')

# simple loop
for filename in files:
    try:
        # open the file in read mode
        f = open(filename, 'r')
    except OSError:
        # handle the case where file does not exist or permission is denied
        print('cannot open file', filename)
    else:
        # do stuff with the file object (f)
        print(filename, 'opened successfully')
        print('found', len(f.readlines()), 'lines')
        f.close()
def divide(x, y):
    try:
        result = x / y
    except ZeroDivisionError:
        print("Cannot divide by zero")
    else:
        print("Result is", result)
    finally:
        print("Finally...")
# Try a number - nothing will print out
a = 321
if hasattr(a, '__len__'):
    print(len(a))

# Try a string - the length will print out (4 in this case)
b = "5555"
if hasattr(b, '__len__'):
    print(len(b))

Pass

if (true) {
}

while (true) {}
if True:
  pass

while True:
  pass

Functions

def printCopyright():
    print("Copyright 2020. Me, myself and I. All rights reserved.")
def greeting(name, saying="Hello"):
    print(saying, name)

greeting("Monica")
# Hello Monica

greeting("Barry", "Hey")
# Hey Barry
# THIS IS BAD CODE AND WILL NOT RUN
def increment(delta=1, value):
    return delta + value
def greeting(name, saying="Hello"):
    print(saying, name)

# name has no default value, so just provide the value
# saying has a default value, so use a keyword argument
greeting("Monica", saying="Hi")

toUpper = lambda s: s.upper()