删除列表中的元素的方式

主要问题是有的时候会少删除

1. 删除之后下标-1
2. 添加到新列表
3. 倒着删
4. 使用切片

students=[{'name':'zhangsan','age':26,'tel':'15895898270','sex':'male','score':100},
  {'name':'Jack','age':12,'tel':'15895812345','sex':'female','score':99},
  {'name':'Marry','age':17,'tel':'15895888888','sex':'female','score':100},
  {'name':"wangwu",'age':29,'tel':'15895891314','sex':'male','score':57},
  {'name': "wangwu", 'age': 29, 'tel': '15895891314', 'sex': 'unknown', 'score': 57},
  {'name':'lisi','age':15,'tel':'15895897501','sex':'unknown','score':23},
  {'name':'Tony','age':19,'tel':'15895890308','sex':'male','score':89},
  {'name':'Nancy','age':25,'tel':'15895891042','sex':'unknown','score':96},
  {'name':'wanghu','age':24,'tel':'1589589999','sex':'unknown','score':35}]
1.删除之后下标-1
i=0
while i<len(students):
    if students[i]['sex']=='unknown':
        students.pop(i)
        i-=1
    i+=1
print(students)
for student in students:
    print(student)

# 2.添加到新列表
new_students=[]
for student in students:
    if student['sex']!='unknown':
        new_students.append(student)
print(new_students)
for student in new_students:
    print(student)

#3.倒着删
for i in range(len(students)-1,-1,-1):
    if students[i]['sex'] =='unknown':
        students.pop(i)
for student in students:
    print(student)


#4.使用切片
count=0
for student in students[:]:
    count+=1
    if student['sex']=='unknown':
        students.remove(student)
print(count)
for student in students:
    print(student)