• True / False
    • Further aspects are available.
  • Casting Booleans
    • Python casts integers to Booleans nicely.
    • bool(1) = True
    • bool(0) = False
      • Anything except 0 is cast as True, for example bool(-1) = True
    • Imaginary 1, such as bool(1j) = True
      • 0 and float zero are both false.
        • bool(0.0 and bool(0j)
    • For strings:
      • bool('True') = True
      • bool('False') = True
        • An empty string is the only False string:
          • bool('') = False
        • For spaces, these are also True, for example bool(' ') = True
    • For Data Structures, bool([]) = False.
      • If anything is placed inside a Data Structure, this equates to True, for example bool([1,2])
    • An empty Dictionary is False –> book({}) = False
    • For the None value that is returned from Functions if you do not provide an explicit return value.
      • bool(None) = False
    • Why is it important to learn about how booleans are cast in Python?
      • Booleans aren’t usually used directly.
      • Usually checking the Boolean values inside an if statement or a for loop.
        • A common situation for booleans is: 
          myList = [1,2]
if myList:
   print('myList has some values in it!')
        • We are casting the value of myList to a boolean.
  • You can also do this: 
    a = 5
b = 5
if a - b:
  print('a and b are not equal!')
a == b
  • The above will not print. A has to equal to B.
  • Boolean Logic
    • Evaluating a situation as to whether or not to go for a walk: ``` weatherIsNice = False haveUmbrella = True

if not haveUmbrella or weatherIsNice: print(‘Stay inside’) else: print(‘Go for a walk’)

* The above outputs `Go for a walk`.
* Python evaluates Booleans left to right.
* To do the same Boolean logic as above, we can do the following:

weatherIsNice = True haveUmbrella = False

if not haveUmbrella and not weatherIsNice: print(‘Stay inside’) else: print(‘Go for a walk’)

* Can also place parenthesis around lines for readability.

weatherIsNice = True haveUmbrella = False

if (not haveUmbrella) and (not weatherIsNice): print(‘Stay inside’) else: print(‘Go for a walk’)

* Can also flip the order of statement for readability.

weatherIsNice = True haveUmbrella = False

if haveUmbrella or weatherIsNice): print(‘Go for a walk’) else: print(‘Stay inside’) ```

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