今日内容概要
- 习题讲解
- 字符串的内置方法
- 列表的内置方法
- 可变类型与不可变类型
今日内容详细
习题讲解
"""
温馨提示：
⽤户名与密码源于字符串 source_data='kevin|123'
想办法从中拆分出⽤户名和密码⽤于后续账户信息⽐对
普通要求：
1. 验证失败情况下可⼀直循环验证，成功则直接退出
拔⾼练习：
1. 只允许三次失败机会
2. 登录成功后进⼊内层循环，⽤户输⼊任何指令利⽤格式化
输出
打印正在执⾏该⽤户指令即可，直到⽤户输⼊字⺟q退出内层
循环
"""
source_data='kevin|123'
# 1.解压赋值
username,password = source_data.split('|')
# 5.添加计数器
count = 1
# 4.循环
while True:
if count == 4:
break
# 2.用户输入
in_name = input("请输入用户名>>>:").strip()
in_password = input("请输入密码>>>:").strip()
# 3.用户名密码判断
if username == in_name and password == in_password:
print("登陆成功")
# 6.用户输入指令
cmd = input("想要执行的指令>>>:").strip()
if cmd == 'q':
break
print("正在执行的指令>>>%s" % cmd)
else:
print("登陆失败")
count += 1
字符串的内置方法
1.大小写转换 str.upper() str.upper()
1.将字符串转换为大写 str.upper(self)
str1 = 'KEvin give ME 12$'
print(str1.upper()) # KEVIN GIVE ME 12$
2.将字符串转换为小写 str.lower(self)
str1 = 'KEvin give ME 12$'
print(str1.lower()) # kevin give me 12$
ps:运用于图片的验证码不区分大小写
3.练习
ag:把用户输入的验证码全部转为大写或者小写，跟原来的验证码都转为大写或者小写进行比较
"""
把用户输入的验证码全部转为大写或者小写，跟原来的验证码都转为大写或者小写进行比较
"""
jpg1 = 'Ds45TJ'
while True:
in_jpg = input("请输入图片上的验证码>>>:").strip()
if jpg1.upper() == in_jpg.upper():
print("正确")
break
else:
print("验证码输入错误")
2.判断字符串是否为大小写 str.isupper() str.islower()
1.判断字符串中的字母是否为大写 str.isupper(self)
str1 = 'KEvin give ME 12$'
str2 = 'KEVin'
str3 = 'KEVIN123'
str4 = 'kevin'
print(str1.isupper()) # False
print(str2.isupper()) # False
print(str3.isupper()) # True
print(str4.isupper()) # False
2.判断字符串是否为小写 str.islower(self)
str1 = 'KEvin give ME 12$'
str2 = 'KEVin'
str3 = 'kevin123'
str4 = 'kevin'
print(str1.islower()) # False
print(str2.islower()) # False
print(str3.islower()) # True
print(str4.islower()) # True
3.判断字符是否以某个字符开头或结尾 str.startswith() str.endswith()
1.判断字符是否以某个字符开头 str.startswith(self, prefix, start=None, end=None)
res = 'Kevin123 OldGirl'
print(res.startswith('kev')) # False
print(res.startswith('Kev')) # True
2.判断字符是否以某个字符结尾 str.endswith(self, suffix, start=None, end=None)
res = 'Kevin123 OldGirl'
print(res.endswith("GIRL")) # False
print(res.endswith('rl')) # True
1.format方法格式化
1.1 按照顺序
str1 = 'my name is {},my age is {}'
print(str1.format('nana',18)) # my name is nana,my age is 18
1.2 按照索引
str1 = '{1} {1}my name is {0},my age is {1} {0}{0}'
print(str1.format('tony',18)) # 18 18my name is tony,my age is 18 tonytony
1.3 按照变量名
str1 = 'my name is {name},my age is {age}'
print(str1.format(name= 'kevin',age = 18)) # my name is kevin,my age is 18
5.字符串的拼接 + str.join()
1.+号
print('hello' + ' '+'world') # hello world
list1 = ['nana','tony','tom']
print(list1[0] +"|"+ list1[1] + "|"+ list1[2]) # nana|tony|tom
2.str.join(self, iterable)
list1 = ['nana','tony','tom']
print('|'.join(list1)) # nana|tony|tom
6.替换字符串 str.replace()
1.str.replace(self, old, new, count=None)
s = 'my name is kevin kevin kevin kevin'
print(s.replace('kevin','jason',2)) # my name is jason jason kevin kevin
print(s.replace('kevin','jason')) # my name is jason jason jason jason
7.判断是否为纯数字
1.str.isdigit(self)
s1 = '123.1'
s2 = '123'
print(s1.isdigit()) # False
print(s2.isdigit()) # True
8.查找一个子字符串在另一个字符串中 的索引 str.find() str.index()
1.str.find(self, sub, start=None, end=None)
msg='tony say hello hello hello'
print(msg.find('say')) # 5
print(msg.find('hello')) # 9
print(msg.find('hellllo')) # -1
2.str.index(self, sub, start=None, end=None)
print(msg.index('say')) # 5
print(msg.index('hello')) # 9
print(msg.index('hellllo')) # ValueError: substring not found
3.index 与find区别
如果一个子字符串在一个字符串里面，那么久返回子字符串第一个字母在字符串里的索引；如果不在，find()方法会返回数字-1，index()方法会报错
9.记录子字符串出现的次数 str.count()
1.str.count(self, sub, start=None, end=None)
s1 = 'hello jello helllo world'
print(s1.count('hello')) # 1
print(s1.count('l')) # 8
print(s1.count('m')) # 0
10.居中展示 左对齐 右对齐 str.center() str.ljust() str.rjust()
1.居中展示 str.center(self, width, fillchar=None)
s1 = 'tony'
print(s1.center(12,'+')) # ++++tony++++
2.左对齐 str.ljust(self, width, fillchar=None)
s1 = 'tony'
print(s1.ljust(12,'+')) # tony++++++++
3.右对齐 str.rjust(self, width, fillchar=None)
s1 = 'tony'
print(s1.rjust(12,'+')) # ++++++++tony
11.字符串大小写格式 str.title() str.capitalize() str.swapcase()
1.字符串中，单词首字母大写 str.title(self)
str1 = 'my name is jason'
print(str1.title()) # My Name Is Jason
2.字符串中，第一个单词大写，其余小写 str.capitalize(self)
str1 = 'my name is jason'
print(str1.capitalize()) # My name is jason
3.字符串中，所有单词大写 str.swapcase(self)
str1 = 'my name is jason'
print(str1.swapcase()) # MY NAME IS JASON
列表的内置方法
1.基本用法
1.类型转换：能够被for循环的数据类型都可以转换成列表（字符串、集合、字典、元组） list()
a = 1
b = 11.2
c = 'kevin'
d = {11,22,44,33}
e = {'name':'NANA','age':18}
f = [11,22,33]
g = (11,22,33,)
print(list(a)) # TypeError: 'int' object is not iterable
print(list(b)) # TypeError: 'float' object is not iterable
print(list(c)) # ['k', 'e', 'v', 'i', 'n']
print(list(d)) # [33, 11, 44, 22]
print(list(e)) # ['name', 'age']
print(list(f)) # [11, 22, 33]
print(list(g)) # [11, 22, 33]
ps :1.整型和浮点型不能够使用该方法
2.字符串用list()方法，返回的额是一个个的字符组成的列表
3.字典用list()方法，返回的是key值组成的列表
4.集合是无序的
2.列表长度 len(*args, **kwargs)
l1 = [1,2,3,4]
print(len(l1)) # 4
3.索引取值
l1 = ['jason', 'kevin', 'oscar', 'tony']
print(l1[0]) # jason
print(l1[-1]) # tony
4.切片操作
l1 = ['jason', 'kevin', 'oscar', 'tony']
print(l1[0:3]) # ['jason', 'kevin', 'oscar']
print(l1[:]) # ['jason', 'kevin', 'oscar', 'tony']
print(l1[-4:-1]) # ['jason', 'kevin', 'oscar']
4.间隔/方向
l1 = ['jason', 'kevin', 'oscar', 'tony']
print(l1[::2]) # ['jason', 'oscar']
2.增
1.末尾追加 list.append(self, p_object)
list1 = [11,33,'nana','kevin']
print(list1.append(55)) # None
print(list1) # [11, 33, 'nana', 'kevin', 55]
2.索引插入
list1 = [11,33,'nana','kevin']
print(list1.insert(2,'jason')) # None
print(list1) # [11, 33, 'jason', 'nana', 'kevin']
3.列表的合并
list1 = [11,33,'nana','kevin']
list1.append([1,2,3,4])
print(list1) # [11, 33, 'nana', 'kevin', [1, 2, 3, 4]]
list2 = [11,33,'nana','kevin']
list2.extend([1,2,3,4])
print(list2) # [11, 33, 'nana', 'kevin', 1, 2, 3, 4]
ps:append()会把列表的整体添加到末尾，extend()是列表的合并
3.删
1.del
list1 = [1,2,3,'jason','kevin']
del list1[1]
print(list1) # [1, 3, 'jason', 'kevin']
del list1[2]
print(list1) # [1, 3, 'kevin']
del list1
print(list1) # NameError: name 'list1' is not defined
2.list.remove(self, value) # 括号里写要删除的值
list1 = [1,2,3,'jason','kevin']
list1.remove('jason')
print(list1)
list1.remove(22) # ValueError: list.remove(x): x not in list
3.list.pop() list.pop(self, index=None) 弹出元素 可以指定索引删除值
list1 = [1,2,3,'jason','kevin']
print(list1.pop()) # kevin
print(list1) # [1, 2, 3, 'jason']
list2 = [1,2,3,'jason','kevin']
print(list2.pop(3)) # jason
print(list2) # [1, 2, 3, 'kevin']
4.改与查
1.改 索引值修改
2.查 切片
可变类型与不可变类型
1.可变类型：值改变，id不变 # 列表
list1 = [1,2,3,4]
print(id(list1)) # 2172934442824
list1.append(5)
print(id(list1)) # 2172934442824
2.不可变类型：值改变，id也改变 # 字符串 整型 浮点型
str1 = 'hello world'
print(id(str1)) #1497913184048
str1.title()
print(id(str1.title())) # 1497913184560
作业
'''使用列表的内置方法实现队、栈两种数据结构'''
list1 =[11,22,33,44,55]
list2 = []
# 1.先进
for i in list1:
list2.append(i)
print(list2) # [11, 22, 33, 44, 55]
# 2.队列 先进先出
for i in list2:
print(i)
print("***************************")
# 3.栈 先进后出
while True:
if len(list2):
print(list2.pop())
else:
break
浙公网安备 33010602011771号