Python class and function json

# coding=utf-8

__author__ = 'student'

'''

how to define a class

how to extend a class

how to make a package

how to import package

how to define a method

'''

str = u"我是中国人"

print str

class Calculator:

    def __init__(self):

        print "I am a Calculator"

    def add(self,op1,op2):

        return op1 + op2

    def divide(self,op1,op2):

        return op1/op2

    def multiply(self,op1,op2):

        return op1*op2

    def subtract(self,op1,op2):

        return op1-op2

    def others(self,expr):

        eval(expr)

c = Calculator()

print c.add(1,2)

print c.subtract(2,10)

print c.others("3*5")

print eval ("3*5")

name = dict(first='Bob', last='Smith')

rec = dict(name=name, job=['dev', 'mgr'], age=40.5)

print rec

import json

S=json.dumps(rec)

print S

json.dump(rec, fp=open('testjson.txt', 'w'), indent=4)

print(open('testjson.txt').read())

p=json.load(open("testjson.txt"))

print p

for x in xrange(1,10,2):

    print x