python基础之列表的坑

#列表的坑之一
list1 = ['python','java','php','c','c++','c#','ruby']
#将索引为奇数的元素删除 ['java','c','c#']
list2 = []
for item in list1:
    if list1.index(item) % 2 != 1:
        list2.pop(list1.index(item))
print(list1) #  ['python', 'php', 'c', 'c#', 'ruby']
#这是因为列表用pop之后,后面的索引都会自动减一

#切片
list1 = ['python','java','php','c','c++','c#','ruby']
list2 = list1[1::2]
print(list2) #['java','c','c#']

#赋值到其他的空列表
list1 = ['python','java','php','c','c++','c#','ruby']
list2 = []
for i in list1:
    if list.index(i)%2==0:
        list2.append(i)
print(list2) # ['java','c','c#']

#倒序删除
list1 = ['python','java','php','c','c++','c#','ruby']
for i in range(len(list1)-1,-1,-1):
    if i % 2 == 0:
        del li[i]
print(list1) #  ['java','c','c#']