python实例，python实例100例,1.平方根　　方法一

python实例，python实例100例,1.平方根　　方法一

1.平方根

　　方法一：

num=float(input(‘请输入数字>>>‘))num_sqrt=num**0.5print(num_sqrt)

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　　方法二：

import cmathnum = int(input(‘>>>‘).strip())num_sqrt=cmath.sqrt(num)print(‘{0}的平方根为{1:0.3f}+{2:0.3f}j‘.format(num,num_sqrt.real,num_sqrt.imag))

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2.三角形面积计算

while True:    a=float(input(‘三角形第一边长>>>‘))    b=float(input(‘三角形第二边长>>>‘))    c=float(input(‘三角形第三边长>>>‘))    if a+b>c and a-b<c:        s=(a+b+c)/2        area=(s*(s-a)*(s-b)*(s-c))**0.5        print(‘面积%f‘%area)        break    else:        print(‘输入的不是三角形‘)        continue

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3.摄氏转华氏温度

celsius=float(input(‘输入摄氏度>>>‘))fahrenheit=(celsius*1.8)+32print(‘%f摄氏度转为华氏温度为%f‘%(celsius,fahrenheit))

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4.判断是不是闰年

year=int(input(‘输入一个年份>>>‘))if(year%4)==0:    if(year%100)==0:        if(year%400)==0:            print(‘{0}是闰年‘.format(year))        else:            print(‘不是闰年‘)    else:        print(‘不是闰年‘)else:    print(‘不是闰年‘)

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5.打印三角形

max_level=input(‘输入行数>>‘)max_level=int(max_level)for current_level in range(1,max_level+1):    for i in range(max_level-current_level):        print(‘ ‘,end=‘‘)    for j in range(2*current_level-1):        print(‘*‘,end=‘‘)    print()

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6.打印倒三角形

max_level=input(‘输入行数>>‘)max_level=int(max_level)for current_level in range(max_level,0,-1):    for i in range(max_level-current_level):        print(‘ ‘,end=‘‘)    for j in range(2*current_level-1):        print(‘*‘,end=‘‘)    print()

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7.打印九九乘法表

for i in range(1,10):    for j in range(1,i+1):        print(‘%s * %s = %s‘%(i,j,i*j),end=‘  |‘)    print()

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8.复制文件

import sysl=sys.argvsource_file_path=l[1]dest_file_path=l[2]with open(r‘%s‘%source_file_path,‘rb‘) as s_f,    open(r‘%s‘%dest_file_path,‘wb‘) as d_f:    for line in s_f:        d_f.write(line)

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9.修改文件

　　方法一：

with open(‘db.txt‘,‘r‘,encoding=‘utf-8‘) as f:    data=f.read()    data=data.replace(‘SB‘,‘aa‘)with open(‘db.txt‘,‘w‘,encoding=‘utf-8‘) as f:    f.write(data)

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　　方法二：

import ostarget_file=r‘db.txt‘intermediary_file=r‘a.txt‘with open(target_file,‘r‘,encoding=‘utf-8‘) as t_f,    open(intermediary_file,‘w‘,encoding=‘utf-8‘) as i_f:    for line in t_f:        if ‘alex‘ in line:            line=line.replace(‘alex‘,‘SB‘)        i_f.write(line)os.remove(target_file)os.rename(intermediary_file,target_file)

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10.购物车

  1 import os  2 product_list = [[‘Iphone 7‘, 5800], [‘Coffee‘, 30], [‘疙瘩汤‘, 10], [‘Python Book‘, 99], [‘Bike‘, 199], [‘vivo X9‘, 2499]]  3 shopping_cart = {}  4 current_userinfo = []  5   6 db_file = r‘db.txt‘  7   8 while True:  9     print(‘‘‘ 10     1 登陆 11     2 注册 12     3 购物 13     ‘‘‘) 14  15     choice = input(‘>>: ‘).strip() 16  17     if choice == ‘1‘: 18         # 1 登陆 19         tag = True 20         count = 0 21         while tag: 22             if count == 3: 23                 print(‘尝试次数过去，退出。。。‘) 24                 break 25             uname = input(‘用户名: ‘).strip() 26             pwd = input(‘密码: ‘).strip() 27  28             with open(db_file, ‘r‘, encoding=‘utf-8‘)as f: 29                 for line in f: 30                     user_info = line.strip(‘\n‘).split(‘,‘) 31                     uname_of_db,pwd_of_db,balance_of_db = user_info 32                     if uname == uname_of_db and pwd == pwd_of_db: 33                         print(‘登陆成功‘) 34  35                         # 登陆成功则将用户名和余额添加道列表 36                         current_userinfo = [uname_of_db, balance_of_db] 37                         print(‘用户信息为: ‘, current_userinfo) 38                         tag = False 39                         break 40                 else: 41                     print(‘用户名或密码错误‘) 42                     count += 1 43  44     elif choice == ‘2‘: 45         uname = input(‘请输入用户名: ‘).strip() 46         while True: 47             pwd1 = input(‘请输入密码: ‘).strip() 48             pwd2 = input(‘再次确认密码: ‘).strip() 49             if pwd2 == pwd1: 50                 break 51             else: 52                 print(‘两次输入密码不一致，请重新输入!!!‘) 53  54         balance = input(‘请输入充值金额: ‘).strip() 55         with open(db_file, ‘a‘, encoding=‘utf-8‘) as f: 56             f.write(‘%s,%s,%s\n‘ % (uname, pwd1, balance)) 57  58     elif choice == ‘3‘: 59         if len(current_userinfo) == 0: 60             print(‘请先登陆。。。‘) 61         else: 62             # 登陆成功后，开始购物 63             uname_of_db = current_userinfo[0] 64             balance_of_db = current_userinfo[1] 65             print(‘尊敬的用户[%s] 您的余额为[%s],祝您购物愉快‘ % (uname_of_db, balance_of_db)) 66  67             tag = True 68             while tag: 69                 for index, product in enumerate(product_list): 70                     print(index, product) 71                 choice = input(‘输入商品编号购物,输入q退出>>: ‘).strip() 72                 if choice.isdigit(): 73                     choice = int(choice) 74                     if choice < 0 or choice >= len(product_list): continue 75  76                     pname = product_list[choice][0] 77                     pprice = product_list[choice][1] 78                     if balance_of_db > pprice: 79                         if pname in shopping_cart:  # 原来已经购买过 80                             shopping_cart[pname][‘count‘] += 1 81                         else: 82                             shopping_cart[pname] = {‘pprice‘: pprice, ‘count‘: 1} 83  84                         balance_of_db -= pprice  # 扣钱 85                         current_userinfo[1] = balance_of_db  # 更新用户余额 86                         print( 87                             "Added product" + pname + "into shopping cart,your current balance" + str( 88                                 balance_of_db)) 89                     else: 90                         print("买不起，穷逼！产品价格是{price},你还差{lack_price}".format(price=pprice, 91                                                                            lack_price=(pprice - balance_of_db))) 92                     print(shopping_cart) 93                 elif choice == ‘q‘: 94                     print(‘‘‘ 95                     --------———已购买商品列表--———————— 96                     id    商品    数量    单价    总价 97  98                     ‘‘‘) 99                     total_cost = 0100                     for i, key in enumerate(shopping_cart):101                         print(‘%22s%18s%18s%18s%18s‘ % (102                             i,103                             key,104                             shopping_cart[key][‘count‘],105                             shopping_cart[key][‘pprice‘],106                             shopping_cart[key][‘pprice‘] *shopping_cart[key][‘count‘]107                         ))108                         total_cost += shopping_cart[key][‘pprice‘] * shopping_cart[key][‘count‘]109 110                     print(‘‘‘111                     你的总花费: %s112                     你的余额为: %s113                     -----------------------end-----------------------    114                     ‘‘‘ % (total_cost, balance_of_db))115 116                     while tag:117                         inp = input(‘确认购买(yes/no?)..: ‘).strip()118                         if inp not in [‘Y‘, ‘N‘, ‘y‘, ‘n‘, ‘yes‘, ‘no‘]: continue119                         if inp in [‘Y‘, ‘y‘, ‘yes‘]:120                             # 将余额写入文件121 122                             src_file = db_file123                             dst_file = r‘%s.swap‘ % db_file124                             with open(src_file, ‘r‘, encoding=‘utf-8‘) as read_f, 125                                     open(dst_file, ‘w‘, encoding=‘utf-8‘) as write_f:126                                 for line in read_f:127                                     if line.startswith(uname_of_db):128                                         l = line.strip(‘\n‘).split(‘,‘)129                                         l[-1] = str(balance_of_db)130                                         line = ‘,‘.join(l) + ‘\n‘131 132                                     write_f.write(line)133                             os.remove(src_file)134                             os.rename(dst_file, src_file)135 136                             print(‘购买成功，请耐心等待发货‘)137 138                         shopping_cart = {}139                         current_userinfo = {}140                         tag = False141                 else:142                     print(‘输入非法‘)143     else:144         print(‘非法操作‘)

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11.注册（函数）

 1 db_path=‘db.txt‘ 2 def uname(): 3     while True: 4         uname = input(‘username>>>‘).strip() 5         if not uname.isalnum():continue 6         with open(r‘%s‘%db_path,‘r‘,encoding=‘utf-8‘)as f: 7             for line in f: 8                 if line.startswith(uname): 9                     print(‘该用户已注册，请重新输入‘)10                     break11             else:12                 return uname13 14 def upwd():15     while True:16         upwd1=input(‘password>>>‘).strip()17         upwd2=input(‘confirm password>>>‘).strip()18         if upwd1==upwd2:19             return upwd120         else:21             print(‘输入不一致，请重新输入‘)22 23 def balance():24     balance=input(‘请输入充值金额>>>‘).strip()25     if balance.isdigit():26         return balance27 28 def db_handle(*args):29     info=‘:‘.join(args)30     with open(r‘%s‘%db_path,‘a‘,encoding=‘utf-8‘) as f:31         f.write(‘%s\n‘ %(info))32 33 def interactive():34     username=uname()35     password=upwd()36     user_balance=balance()37     return username,password,user_balance38 39 username,password,user_balance=interactive()40 print(username)41 print(password)42 print(user_balance)43 44 db_handle(username,password,user_balance)

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12.昨天是哪天

1 import datetime2 def get_yesterday():3     today=datetime.date.today()4     oneday=datetime.timedelta(days=1)5     yesterday=today-oneday6     return yesterday7 8 print(get_yesterday())

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13.计算某月的第一天是星期几，该月有几天

1 import calendar2 year=int(input(‘输入年份>>>‘).strip())3 mon=int(input(‘输入月份>>>‘).strip())4 month_range=calendar.monthrange(year,mon)5 week,num=month_range6 print(‘该月的第一天是星期{week},该月有{num}天‘.format(week=week+1,num=num))7 cal=calendar.month(year,mon)8 print(‘该月的日历为：‘)9 print(cal)

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