LPTHW Exercises 27 - 31

(12/2/13 -- 6:30pm PST)




Control Flows

Review


  1. Known Python data types?
  2. What are functions?  How do we define and call them?
  3. What is scope?  Local?  Global?

Boolean Data Type


One of two values (True or False)

Think of it like a light switch

It represents either on or off

Exercise 27: Truth Expressions

bool() --> convert a data type into a Bolean value
True -->  Boolean data type.  On switch (declares something is truth)

False --> Boolean data type. Off switch (declares something is false)
and --> Operator. Produces True if ALL operands are true, else False or --> Operator. Produces True if ANY operands are true, else False
not --> Operator. Produces inverse Boolean (not True == False)
== --> Operator. Does equal (5 ==3)!= --> Operator. Does not equal (5 !=3)
>= --> Operator. Greater than OR equal to (4 >=3)
<= --> Operator. Less than OR equal to (2 <=3)

Problem Set: Truth Tables


See "problem_set_two.py" in the IDE

Exercise 28: Boolean Logic Expressions

not (1 == 1 and 0 != 1)
not (10 == 1 or 1000 == 1000)

not ("testing" == "testing" and "Zed" == "Cool Guy")
1 == 1 and not ("testing" == 1 or 1 == 0)
"chunky" == "bacon" and not (3 == 4 or 3 == 3)
3 == 3 and not ("testing" == "testing" or "Python" == "Fun")
  • Find an equality test (== or !=) and replace it with its truth.
  • Find each and/or inside parentheses and solve those first.
  • Find each not and invert it.
  • Find any remaining and/or and solve it.

  • IF statements

    How do we create different branches or flows?

    people = 20
    cats = 30
    dogs = 15
    
    
    if people < cats:
        print "Too many cats! The world is doomed!"
    
    if people > cats:
        print "Not many cats! The world is saved!"
    
    if people < dogs:
        print "The world is drooled on!"
    
    if people > dogs:
        print "The world is dry!"
    
    
    dogs += 5
    
    if people >= dogs:
        print "People are greater than or equal to dogs."
    
    if people <= dogs:
        print "People are less than or equal to dogs."
    
    
    if people == dogs:
        print "People are dogs."

    Else/Elif Statements


    How about many branches?

    people = 30
    cars = 40
    buses = 15
    
    
    if cars > people:
        print "We should take the cars."
    elif cars < people:
        print "We should not take the cars."
    else:
        print "We can't decide."
    
    if buses > cars:
        print "That's too many buses."
    elif buses < cars:
        print "Maybe we could take the buses."
    else:
        print "We still can't decide."
    
    if people > buses:
        print "Alright, let's just take the buses."
    else:
        print "Fine, let's stay home then."

    Control Flow: conditional statements and loops

    By benjaminplesser

    Control Flow: conditional statements and loops

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