Python 4- more operations

# Remainder - modular arithmetic

# systematically restrict computation to a range
# long division - divide by a number, we get a quotient plus a remainder
# quotient is integer division //, the remainder is % (Docs)


# problem - get the ones digit of a number
num = 49
tens = num // 10      #除号在python里面是//
ones = num % 10    #求余数
print tens, ones
print 10 * tens + ones, num





# application - 24 hour clock
# http://en.wikipedia.org/wiki/24-hour_clock

hour = 20
shift = 8
print (hour + shift) % 24




# application - screen wraparound
# Spaceship from week seven

width = 800
position = 797
move = 5
position = (position + move) % width
print position




# Data conversion operations

# convert an integer into string - str
# convert an hour into 24-hour format "03:00", always print leading zero

hour = 3
ones = hour % 10
tens = hour // 10
print tens, ones, ":00"
print str(tens), str(ones), ":00"
print str(tens) + str(ones) + ":00"

# convert a string into numbers using int and float



# Python modules - extra functions implemented outside basic Python

import simplegui    # access to drawing operations for interactive applications

import math             # access to standard math functions, e.g; trig

import random       # functions to generate random numbers


# look in Docs for useful functions

print math.pi