2018.10.10作业

# 1、将names=['egon','alex_sb','wupeiqi','yuanhao']中的名字全部变大写
# names = ['egon', 'alex_sb', 'wupeiqi', 'yuanhao']
# name = [a.upper() for a in names]
# print(name)
# 2、将names=['egon','alex_sb','wupeiqi','yuanhao']中以sb结尾的名字过滤掉，然后保存剩下的名字长度
# names = ['egon', 'alex_sb', 'wupeiqi', 'yuanhao']
# name2 = [len(a) for a in names if not a.endswith('sb')]
# print(name2)
# 3、求文件a.txt中最长的行的长度（长度按字符个数算，需要使用max函数）
# with open('a.txt', 'r', encoding='utf-8')as f:
#     print(max(len(lines) for lines in f))
# 4、求文件a.txt中总共包含的字符个数？思考为何在第一次之后的n次sum求和得到的结果为0？（需要使用sum函数）
# with open('a.txt', 'r', encoding='utf-8')as f:
#     print(sum(len(lines) for lines in f))
# 5、思考题
#
# with open('a.txt') as f:
#     g=(len(line) for line in f)
# print(sum(g))
# 为何报错？
# 对已关闭的文件进行了操作
# 6、文件shopping.txt内容如下
#
# mac,20000,3
# lenovo,3000,10
# tesla,1000000,10
# chicken,200,1
# 求总共花了多少钱？
# with open('shopping.txt', 'r')as f:
#     count = 0
#     for lines in f:
#         list1 = lines.split(',')
#         count += int(list1[1]) * int(list1[2])
# print(count)
# 打印出所有商品的信息，格式为[{'name':'xxx','price':333,'count':3},...]
# shopping_dic = []
# with open('shopping.txt', 'r')as f:
#     for lines in f:
#         list1 = lines.split(',')
#         message1 = list1[2][0:len(list1[2]) - 1]
#         shopping_dic.append({'name': list1[0], 'price': list1[1], 'count': message1})
# print(shopping_dic)
# 求单价大于10000的商品信息,格式同上
# shopping_dic = []
# with open('shopping.txt', 'r')as f:
#     for lines in f:
#         list1 = lines.split(',')
#         message1 = list1[2][0:len(list1[2]) - 1]
#         if int(list1[1]) > 10000:
#             shopping_dic.append({'name': list1[0], 'price': list1[1], 'count': message1})
# print(shopping_dic)

# 查找一个值是否存在于列表中并返回索引
# list1 = [1, 2, 10, 30, 33, 99, 101, 200, 301, 402]
# 
# 
# def search(num, l, start=0, stop=len(list1) - 1):
#     if start <= stop:
#         mid = start + (stop - start) // 2
#         # print('start:[%s] stop:[%s] mid:[%s] mid_val:[%s]' % (start, stop, mid, l[mid]))
#         if num > l[mid]:
#             start = mid + 1
#         elif num < l[mid]:
#             stop = mid - 1
#         else:
#             print('find it in', mid)
#             return
#         search(num, l, start, stop)
#     else:
#         print('not exists')
#         return
# search(301, list1)