Python 3.4.2 (v3.4.2:ab2c023a9432, Oct  5 2014, 20:42:22) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
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>>> # Python shell session (edited) for Lecture 2
>>> # We went over numbers of different bases
>>> # decimal is base 10; binary is base 2; octal is base 8
>>> # characters are stored as "ascii codes"; see Appendix C of the text
>>> # operator precedence:
>>> # **; then *  /  //  %; then + -
>>> # ()'s override precedence
>>> 4 + 5 ** 3
129
>>> (4 + 5) ** 3
729
>>> 4 + 5 * 3
19
>>> (4 + 5) * 3
27
>>> #integer division throws out the decimal part
>>> 5//2
2
>>> #modulus returns the remainder after integer division
>>> 5 % 2
1
>>> # use the "help" function!
>>> help(abs)
Help on built-in function abs in module builtins:

abs(...)
    abs(number) -> number
    
    Return the absolute value of the argument.

>>> # All objects have types
>>> 7
7
>>> type(7)
<class 'int'>
>>> type(34.64)
<class 'float'>
>>> type(8e-2)
<class 'float'>
>>> type('hello world')
<class 'str'>
>>> # you can convert from one type to another
>>> int(7.999)
7
>>> float(4)
4.0
>>> str(123)
'123'
>>> int("12")
12
>>> int("hello")  # this doesn't make sense so get an error
Traceback (most recent call last):
  File "<pyshell#31>", line 1, in <module>
    int("hello")  # this doesn't make sense so get an error
ValueError: invalid literal for int() with base 10: 'hello'
>>> # i = j   and j = i mean different things in programming languages!
>>> i = 4
>>> j = 3
>>> i = j
>>> i
3
>>> j
3
>>> i = 4
>>> j = 3
>>> j = i
>>> i
4
>>> j
4
>>>