li = [1,2,3,4] # [1,3,4]
# 索引值是奇数的删除
for i in range(4):
if i % 2 == 1:
li.pop(i) # 会报错
print(li)
面试题:
li = [1,2,3,4,5] #[1,3,4,5]
# 索引值是奇数的删除
for i in range(4):
if i % 2 == 1:
li.pop(i) # 结果不对
print(li)
li = [1,2,3,4,5]
for i in range(len(li)-1,-1,-1):
if i % 2 == 1:
li.pop(i) # 倒序删除
print(li)
偷换感念
li = [1,2,3,4,5]
new_li = []
for i in range(len(li)):
if i % 2 == 1:
new_li.append(li[i])
for em in new_li:
li.remove(em)
print(li)
li = [1,2,3,4,5]
for i in range(len(li)-1,-1,-1):
if i % 2 == 1:
del li[i] # 倒序删除
print(li)
li = [1,2,3,4,5]
del li[1::2]
print(li)
使用for删除列表的时候从左向右删除,会报错.结果不对
dic = {"k1":"v1","k2":"v2"}
for i in dic:
dic["k3"] = "v3"
print(dic)
面试题:
li = [1,2,3,4]
for i in li:
li.append(i)
print(li)
不能在遍历字典本身中改变大小,要批量删除字典的键值对
dic = {"k1":"v1","k2":"v2","k3":"v3"}
for i in dic:
dic["k7"] = "1"
print(dic)
li = []
for i in dic:
if i == "k1" or i == "k3":
li.append(i)
for em in li:
dic.pop(em)
print(dic)
