菜鸟python---以后会遇到的坑

死循环
lst = [1,2,3]
for i in lst:
    lst.append(4)
print(lst)

lst = [11,22,33,44]
for i in lst:
    lst.remove(i)
print(lst)

for i in lst:
    del lst[-1]
print(lst)

lst = [11,22,33,44]
for i in lst:

lst = [11,22,33,44]
for i in range(len(lst)):
    del lst[-1]
print(lst)

for i in range(len(lst)):
    lst.pop()
print(lst)

lst = [11,22,33,44]
lst1 = lst[:]
for i in lst1:
    lst.remove(i)
print(lst)

使用for循环清空列表元素内容
1.从后向前删除, 2.创建一个新的容器,循环新的容器删除旧的容器内容

面试题:

    lst = [1,[2]]
    lst[1] = lst
    print(lst)
    答案: [1, [...]]

字典和集合:
dic = {"key":1,"key1":2}

for i in dic:
    if i == "key1":
        dic[i] = dic[i] + 8  # dic[i] = 10
    else:
        print("没有这个键!")
print(dic)

字典和集合在遍历(循环)时不能修改原来的大小(字典的长度),可以进行修改值
s = {1,2,3,4,5,6}
for i in s:
    s.pop()
print(s)