Wk1Lec2.txt

WEEK 1, LECTURE 2

Operators on ints and floats
    +
    -
    *
    **  This is the exponent, e.g. 3**3 = 27
    /
    %   This gives you the remainder, see below
Division
NOTE: 
    Works fine if at least one of the number is a float.
    HOWEVER, if both are ints, the result is an int, which
    is the "quotient without taking the remainder"
    e.g.:   3.0/2.0 = 1.5
            3.0/2 = 3/2
            3/2 = 1
    To get the REMAINDER, use %.
    e.g.    5%2 = 1
##
Operator Precedence
    Just remember to use brackets...
##
Comparison Operators on ints and floats
    >
    >=
    <
    <=
    ==  REMEMBER that a single equals sign, =, ASIGNS the value.
        You need two of them, ==, to evaluate if two values are
        the same or not
    !=
    
    This can be used on ints, and returns True or false
    e.g.: 
        3>2
        True
        3>4
        False
        
    a and b : True if both are True
    a or b  : True if either is True
##
Type Conversion
    float()
    int()
    str()
    
    e.g.:    float(3) = 3.0
             int(3.9) = 3   
 #################################################
 ##           Variables and Naming              ##
 #################################################
 e.g.:
    pi = 3.14159
    radius = 11.2
    area = pi * (radius**2)
    
    NOTE that when you print area, this is not dynamic.
    Therefore, if I change the value of radius, area is not 
    automatically reevaluated. Instead I have to reset it.
    
    radius = 15
    area = pi * (radius**2)
##
None-Scalar Objects
    strings : str in python
    
Operations on strings
    *               e.g.: 3 * 'ab' = 'ababab'
    +               e.g.: 'a'+'b' = 'ab'
    len()           e.g.: len('abc') = 3
    'str'[#]        Indexing, see below
    'str'[-#]
    'str'[#1:#2]    Returns a substring, starting at and
                    including #1, all the way up to, but
                    NOT including, #2
                      
Indexing
    e.g.:     'abc'[0] = 'a'
              'abc'[-1] = 'c'  
              'abc'[0:2] = 'ab'
##
Getting Input form the User

    Use raw_input('a prompt')
  
    e.g.:   name = raw_input('please type your name')
 #################################################
 ##             Branching Programs              ##
 #################################################   

if <<something>> == <<something>>:
    <<some code>>
else:
    <<some other code>>

e.g.:
import time
UserInt = int(
    raw_input(
         'Please type an int. We will then tell you if it is an '
        +'even or odd number.'
        +'\n'
    )
)
print('')
time.sleep(1)
##
if UserInt % 2 == 0:
    print('Your number is even')
else:
    print('It is odd!') 
print('') 
time.sleep(1)
##
print('This has been another MA original.')