作业12

一、实现将列表内的值全部变为大写

names=['egon','alex_sb','wupeiqi','yuanhao']
new_name = [line.upper() for line in names]
print(new_name)

二、将列表内的结尾带有sb的值全部过滤，保留其余列表内值的长度

names=['egon','alex_sb','wupeiqi','yuanhao']

new_name = []
for line in names:
    if not line.endswith('sb'):
        new_name.append(line)
print(new_name)
new_name = [line for line in names if not line.endswith('sb')]
print(new_name)

三、求文件中最长行的长度，需使用max函数

with open('test.txt') as f1:
    print(max(len(line) for line in f1))

四、求文件内一共包含的字符个数，并思考为何在第一次之后的n次sum求和得到的结果为0

with open('test.txt') as f1:
    print(sum(len(line) for line in f1))
    print(sum(len(line) for line in f1)) 【res = 0# 文件未关闭基于上一次的读取文件指针是在文件末尾】

五、思考为何报错

with open('a.txt') as f:
    g=(len(line) for line in f)
print(sum(g)) 


g目前是一个迭代器对象不可以计算总和

六、

1.求购物车文件内的总价

2.打印所有商品信息，格式为字典形式

3.求所以单价大于10000的商品，格式同上

shop_car = []
with open('test.txt',mode='rt',encoding='utf-8') as f1:
    for line in f1:
        res = line.strip('\n').split(',')
        data = {'name':res[0],'price':int(res[1]),'count':int(res[2])}
        shop_car.append(data)
print(shop_car)


print(sum(line['price'] * line['count'] for line in shop_car))

new_shop = [line for line in shop_car if line['price'] > 10000]
print(new_shop)

七、实现判断用户输入的数字是否存在于列表（不使用 in）

nums = [1, 2, 3, 4, 5, 6, 7, 8, 9]
def beanry_search(find_num,nums):
    print(nums)
    if len(nums) == 0:
        print('no here')
        return
    mid_index = len(nums) // 2
    if find_num > nums[mid_index]:
        nums = nums[mid_index+1:]
        beanry_search(find_num,nums)
    elif find_num < nums[mid_index]:
        nums = nums[:mid_index]
        beanry_search(find_num,nums)
    else:
        print('is here!')
beanry_search(3,nums)

八、实现将用户输入的数字的索引值取出（不使用 index）

l = [1,5,67,78,123,456,467,678,1000]
def beanry_cearch(num,l,star=0,stop = len(l) -1):
    if star <= stop:
        middle = star+(stop - star) // 2
        print('start:[%s] stop:[%s] middle:[%s] mid_val:[%s]'%(star,stop,middle,l[middle]))
        if num > l[middle]:
            star = middle+1
        elif num < l[middle]:
            stop = middle-1
        else:
            print('find it',middle)
            return
        beanry_cearch(num,l,star,stop)
    else:
        print('no exits')
        return
beanry_cearch(456,l)