''' Purpose: demonstrate arithmetic and use of variables for naming things

    Something to remember: Python represents an integer as an int
'''

# computers can only store/represent a certain amount of numbers; cannot represent
# every number possible

# basic unit of measure of representation in computers is a bit,
# hence intsy_bitsy
# int = type of number = integers (-3, -2, -1, 0, 1, 2, 3, ...)
# float = decimal numbers
# use 64 bits for ints and floats --> finite amount of numbers that computers can represent

# we can create libraries, containing different functions for us to use in other programs

# get a hold of the pause library (module)
import pause # the pause library has a function to pause the running of our program
# to access a library, we say import --> then we can access the functions inside the library
# import is a key word! --> the structure: import name_of_library
# CANNOT use import/any key word as an identifier

# name some values
a = 33         # integer
b = 23         # integer
c = -256       # negative integer
d = 6.9        # decimal

# ... means placeholder until you replace it with something;
# == is the mathematical equal sign - we'll get here later (don't worry about it right now)
# = is the ASSIGNMENT operator, it is NOT mathematical equal sign
# a = 49, we are assigning the int 49 to the identifier a
# numbers do NOT need quotes; this is IMPORTANT
# now every time after this that you are using a, a will represent the integer 49
# so on with b, c, d
# identifiers also do NOT need quotes

print()

print( 'Values of interest' )

print()

# formatting the print statements
print( 'a =', a )   # we have the string 'a =' exactly, then also print the VALUE of a (which is 49) -
# using identifiers do not need quotes
print( 'b =', b )   # same with the rest
print( 'c =', c )
print( 'd =', d )

print()

pause.until_ready() # this will pause your program
# the function until_ready() is a function within the pause library that we imported
# note the snake_case style for the name of the function until_ready()
# the program will pause until the user hits the enter key in the console
# once you've hit enter, it will run the program unless you encounter another pausing point
# don't use this in your homework

print()

# perform and display some integer calculations
# operators are like +, -, *, /, //, %, **
# operands are things around the operators
total        = a +  b  # a = 33, b = 23 (from earlier) --> a + b == 33 + 23 == 56
difference   = a -  b  # a = 33, b = 23 --> a - b == 33 - 23 = 10
product      = a *  b  # multiplication
dec_quotient = a /  b  # decimal division --> includes the decimal places up to 15 decimal places
int_quotient = a // b  # integer division --> does division, then removes the decimal places; does NOT round
remainder    = a %  b  # remainder operator --> gives you the remainder of the division; NOT the quotient
power        = a ** b  # exponentiation, NOT ^

a ** b # gives you back a value, but cannot use it later without assigning the value to an identifier
# since the above identifiers are numbers, you can do further arithmetic, or use them in print statements
# like below

total_divides_difference = total / difference # 56 / 10 --> 5.6

print( 'Calculations' )

print()

print(  'a + b  =', total )         # we've determined what total is on line 64; total is an identifier
print(  'a - b  =', difference )
print(  'a * b  =', product )
print(  'a / b  =', dec_quotient )
print(  'a // b =', int_quotient )
print(  'a % b  =', remainder )
print(  'a ** b =', power )

print()

pause.until_ready()

print()

# introduce some other built-in functions
abs_c   = abs( c )    # abs(c) gives you the absolute value of c (whatever c is)
float_c = float( c )  # float(c) gives you the decimal version of c (whatever c is)
int_d   = int( d )    # int( d ) gives you the integer version of d

print( 'abs( c )   =', abs_c )
print( 'float( c ) =', float_c )
print( 'int( d )   =', int_d )