进入Python世界——Python基础知识

本文通过实例练习Python基础语法, python版本2.7

# -*- coding: utf-8 -*-
import random

import re
import requests
from bs4 import BeautifulSoup


#  爬取糗事百科的首页内容
def qiushibaike():
    content = requests.get('http://www.qiushibaike.com/').content
    soup = BeautifulSoup(content, 'html.parser')
    # print(soup.get_text())
    for div in soup.find_all('div', {'class': 'foot'}):
        print(div.text.split())
    # for div in soup.find_all('div', {'class': 'content'}):


#  字符串常见处理方法
def demo_string():
    stra = 'hello world'
    print(stra.capitalize())
    print(stra.replace('world', 'victor'))
    strb = '     

hello world  
'
    print(0, strb)
    print(1, strb.lstrip())
    print(2, strb.rstrip(), 'xx')
    strc = 'hello w'
    print(3, strc.startswith('hel'))
    print(4, strc.endswith('w'))
    print(5, stra + strb + strc)
    print(6, len(stra), len(strb), len(strc))
    print(7, '-'.join(['a', 'b', 'c']))  # a-b-c
    print(8, strc.split(' '))
    print(9, strc.find('llo'))


#  运算符操作
def demo_operation():
    print(1, 1 + 2, 5 / 2, 5 * 2, 5 - 2)
    print(2, 1 + 2, 5.0 / 2, 5 * 2, 5 - 2)
    print(3, True, not True, False, not False)
    print(4, 1 << 2, 88 >> 2)
    print(5, 1 < 2, 5 > 3)
    print(6, 5 & 3, 5 ^ 3, 5 | 3)
    x = 3
    y = 5.0
    print(7, x, y, type(x), type(y))


#  函数
def demo_buildinfunction():
    print(1, max(1, 2), min(5, 3))
    print(2, len('xxx'), len([3, 4, 5]))
    print(3, abs(-2), abs(7))
    print(4, range(1, 10, 2))
    # print(5, '
'.join(dir(list)))
    x = 2
    print(6, eval('x+3'))
    print(7, chr(65), ord('a'))
    print(8, divmod(11, 3))


#  控制流
def demo_controlflow():
    score = 65;
    if score > 99:
        print(1, 'A')
    elif score > 60 & score <= 99:
        print(2, 'B')
    else:
        print(3, 'C')
    while score < 100:
        print(4, score)
        score += 10
        if score > 80:
            break
    for i in range(0, 10):
        if i == 0:
            pass
        if i == 3:
            continue
        if i < 5:
            print(5, i*i)
        if i == 7:
            break


#  列表
def demo_list():
    lista = [1, 2, 3]
    print(1, lista)
    # print(dir(list))
    listb = ['a', 1, 1.0, 4, 2]
    print(2, listb)
    lista.extend(listb)
    print(3, lista)
    print(4, len(lista))
    print(5, 'a' in lista, 'b' in listb)
    lista += listb
    print(lista)
    listb.insert(0, 'www')
    print(listb)
    listb.pop(1)
    print(listb)
    # listb.sort()
    print(listb)
    print(6, listb[0], listb[1], listb[2])
    print(7, [0] * 10)
    print(8, listb * 2)
    listb.reverse()
    print(9, listb)
    t = (1, 2, 3,1)
    print(10, t)
    # print(11, t.count())
    print(11, t.count(1), len(t))


# 字典
def demo_dict():
    dicta = {4 : 16, 1 : 1, 2 : 4, 3 : 9, 'a' : 'b'}
    print(1, dicta)
    print(2, dicta.keys(), dicta.values())
    for key, value, in dicta.items():
        print(key, value)
    for key in dicta.keys():
        print(key)
    # 2.0版本是has_keys()方法
    print(3, dicta.__contains__(1), dicta.__contains__(11))
    dictb = {'+': add, '-': sub}
    print(4, dictb.get('-')(5, 3))
    print(4, dictb['+'](1, 2))
    print(5, dictb.__contains__('+'))
    del dictb['+']
    print(5, dictb.__contains__('+'))
    print(5, dictb)

    dictb.pop('-')
    print(6, dictb)

    dictb['x'] = 'y'
    print(7, dictb)


def add(a, b):
    return a + b


def sub(a, b):
    return a - b


# 集合
def demo_set():
    lista = [1, 2, 3]
    lista1 = (1, 2, 3)
    seta = set(lista)
    seta1 = set(lista1)
    print(1, seta)
    print(1, seta1)

    setb = set((2, 3, 4))
    print(2, seta.intersection(setb))
    print(3, seta & setb)
    print(4, seta | setb, seta.union(setb))
    print(5, seta - setb, setb - seta)
    seta.add('xxx')
    print(6, seta)
    print(7, len(seta))
    print(8, seta.isdisjoint(set((1, 2))))
    print(9, 1 in seta)


#  类
class User:
    type = 'USER'

    def __init__(self, name, uid):
        self.name = name
        self.uid = uid

    def __repr__(self):
        # toStirng()
        return 'i am ' + self.name + ' ' + str(self.uid) + ' ' + self.type


# 继承
class Guest(User):
    type = 'GUEST'

    def __repr__(self):
        return "I am guest: " + self.name + ' ' + str(self.uid) + ' ' + self.type


class Admin(User):
    type = 'ADMIN'

    def __init__(self, name, uid, group):
        User.__init__(self,name, uid)
        self.group = group

    def __repr__(self):
        return 'I am admin: ' + self.name + ' ' + str(self.uid) + ' ' + self.group + ' ' + self.type


def create_user(type):
    if type == 'USER':
        return User('u1', 1)
    elif type == 'ADMIN':
        return Admin('a1', 1, 'shu')
    else:
        return Guest('g1', 1)


#  异常
def demo_exception():
    try:
        print(2/1)
        # print(2/0)
        raise Exception('Raise Error', 'xxx')
    except Exception as e:
        print('error', e)
    finally:
        print('clean up')


def demo_obj():
    user1 = User('victor', 1)
    print(user1.__repr__())
    print(user1)
    guest = Guest('xunuo', 2)
    print(guest)
    admin = Admin('Qingde', 2, 'shanghai university')
    print(admin)
    print(create_user('ADMIN'))


def demo_random():
    random.seed(11)
    for i in range(0, 5):
        print(1, random.randint(0,100))
    print(2, int(random.random()*100))
    print(3, random.choice(range(0, 100, 5)))  # 抽奖
    print(4, random.sample(range(0, 100, 10), 4))  # 抽几个

    lista = [1, 2, 3, 4, 5]
    random.shuffle(lista)
    print(lista)


def demo_regex():
    str = 'abc123def12gh15'
    p1 = re.compile('[d]+')
    p2 = re.compile('d')
    print(1, p1.findall(str))
    print(2, p2.findall(str))

    str1 = 'axxx@163.com, bsad@google.com, cdd@qq.com, dasd@qq.com, eda@163.com'
    p3 = re.compile('[w]+@[163|qq]+.com')  # 不能有空格
    print(3, p3.findall(str1))

    str = '<html><h>title</h><body>content</body></html>'
    p4 = re.compile('<h>[^<]+</h>')
    print(4, p4.findall(str))

    p4 = re.compile('<h>[^<]+</h><body>[^<]+</body>')
    print(5, p4.findall(str))

    str = 'xx2017-06-06zzz'
    p5 = re.compile('d{4}-d{2}-d{2}')
    print(6, p5.findall(str))

if __name__ == '__main__':
    # print('hello world')
    qiushibaike()
    # demo_string()
    # demo_operation()
    # demo_buildinfunction()
    # demo_controlflow()
    # demo_list()
    # demo_dict()
    # demo_set()
    # demo_obj()
    # demo_exception()
    # demo_random()
    # demo_regex()