# 7/8讲的是切片
# 内容回顾
# a = "asdasdafsafds"
# print(a[-1])
# print(a[-3:])

# break continue 区别
# print(len(a)) 计算字符串的长度

# a = "asssdjbsa"
# b = a.count("a")
# print(b)

# a = "asssdjbsa"
# b = a.replace("a", "666", 2)  # 这里只能输入的是正数，替换功能
# print(b)

# 把a以空格分割，分为四个部分
# a = "asdasvascasx"
# b = a.split("a", 2)  # 后面的参数就是分割的次数
# print(b)

# count replace find index split
# a = "abcdEFG"
# b = a.capitalize()
# print(b)
# b = a.startswith("ab")  # 检测是不是以ab开头的。
# print(b)

# b = a.lower() 全部变小写
# b = a.upper()  全部变成大写
# b = a.title()  把首字母变成大写

# count replace find index split
# lower 把所有大写变成小写
# lower/upper/title/startswith/endswith/capitalize/title

# a = " haha haha   "
# b = a.strip()
# print(b)


# a = "haha"
# b = a.ljust(10, "6")
# print(b)
# 这个就是填充功能

# a = "hahaha"
# b = a.partition("h")
# print(b)
# 这个是以某个字符分割

# a = ['', 'h', 'ahaha']
# b = ''.join(a)
# print(b)
# 列表转换成字符串

# 10节课的内容
# count/replace/rfind/rindex/split
# ljust/upper/startswith/endswith/capitalize/title
# ljust/rjust/strip/rstrip/lstrip/center/partition/join/rpartition

# istitle/isupper/islower/isspace/isdigit/...
# 所有有is的都是去做判断，以上都是我们字符串说的判断方法。

# 经常去用到的count/replace/rfind/rindex/split
# rjust join startswith endswith    看到他们要知道是什么意思

# sql = "select * from students where id ='1';"  这里就是单双引号的区别

# python 内部查询的方法
# print(help(str.count))

# 字符串的内容---可以看课件

# my_list = [1, 3.14, "hahah"]
# print(my_list[0])

# my_list = list('abcd')
# print(my_list)

# my_list = [12, 212, 21, 321, 31, 2]
# for i in my_list:
#     print(i)
# 使用for循环

# i = 0
# while i < len(my_list):
#     print(my_list[i])
#     i += 1
# 使用 while

# my_list = [12, 212, 21, 321, 31, 2]
# print(id(my_list))
# my_list.append([1])
# print(id(my_list))

# my_list = ["haha", "heihei"]
# my_list.extend(["hahahah", "xzczxc"])
# print(my_list)

# my_list.insert(1, "heihaha")
# print(my_list)

# append extend insert

my_list = [12, 212, 21, 321, 31, 2, 12]
# my_list[1] = 666
# print(my_list)

# a = my_list.count(12)
# print(a)

# if 12 in my_list:
#     print("hhaha")
# else:
#     print("hehehhe")

# del my_list[10]
# print(my_list)

# my_list.remove(321)
# print(my_list)

# 增: extend,append,insert
# 删：del,pop,clear,remove
# 改：下标
# 查：index, count, index, not in