# ascii 只能显示英文，特殊字符和数字
# 万国码：unicode 最开始为16位，之后为32字节
# 升级版：utf-8 utf-16 utf-32
# utf-8: 最少用一个字节，一个字节表示一个英文
# 欧洲16位，两个字节
# 亚洲24位 三个字节
# gbk 国产编译器。只能用于中文和ascii码中的文字
注释
'''
#多行注释(这位单行注释)
print('你好世界')
'''
View Code变量的赋值
1 name1 = '123'
2 name2 = "02"
3 name3 = name2
4
5 print(name1, name2, name3)
View Code
python中常量表示的方法
View Code
在Python3里不再有long类型了，全都是int
在Python中,加了引号的字符都被认为是字符串！
用户交互
1 name = input('请输入用户名: ')
2 print(name, type(name))
View Code
input接收的所有输入默认都是字符串格式！
1 age = int( input("Age:") )
View Code
pratice
1 name = input('what is your name
')
2 age = input('how old are you
')
3 hometown = input('where are you from
')
4
5 print(name + '
' + age + "
" + hometown)
6 #作用就是复制自己多少次，在拼接在一起
7 #只能字符串和字符串拼接
8 print(name * 10)
格式化输出练习
1 print('------------ info of Alex Li -----------')
2 name = input('what is your name
')
3 age = input('how old are you
')
4 job = input('what is your job
')
5 hobby = input('what is your hobby
')
6
7 print('Name : ' + name)
8 print('Age : ' + age)
9 print('Job : ' + job)
10 print('hobby : ' + hobby)
11 print('------------- end -----------------')
if else 语句
1 age = 20
2 if age > 18:
3 print("You are a adult.")
4 else:
5 print("You are a child.")
条件语句的运用
1 num = 20
2 GuessNum = int(input('Please Enter the number you guess：'))
3
4 if GuessNum > 20:
5 print('Big')
6 elif GuessNum == 20:
7 print('Bigon')
8 else:
9 print('small')
10
11 grade = int(input('Please input a grade' + '（
I will give your level）: '))
12
13 if grade > 100:
14 print('Error input')
15 elif grade > 90:
16 print('A')
17 elif grade > 80:
18 print('B')
19 elif grade > 70:
20 print('C')
21 elif grade > 60:
22 print('D')
23 else:
24 print('E')
#while else 的使用
#while 后面的else 作用是指，
#当while 循环正常执行完，中间没有被break 中止的话，就会执行else后面的语句
1 count = 0
2 while count <= 5:
3 count += 1
4 print(count)
5
6 else:
7 print('循环结束')
8
9 count = 0
10 while count <= 5:
11 count += 1
12 print(count)
13 break
14 else:
15 print('循环结束')
#pratice 1
#1、使用while循环输入 1 2 3 4 5 6 8 9 10
1 i = 0
2 while i < 10:
3 i = i + 1
4 print(i)
5 if i == 7:
6 continue
#pratice 2
#求1-100的所有数的奇数和
1 i = 0
2 sum = 0
3 while i < 100:
4 i = i + 1
5 sum += i
6 print(sum)
#pratice 3
#求1-100的所有数的奇数和
1 i = 0
2 sum = 0
3 while i < 100:
4 i = i + 1
5 if i % 2 != 0 or i == 1:
6 sum += i
7 else:
8 continue
9 print(sum)
#pratice 4
#求1-100的所有数的偶数和
1 i = 0
2 sum = 0
3 while i < 100:
4 i = i + 1
5 if i % 2 == 0 and i != 1:
6 sum += i
7 else:
8 continue
9 print(sum)
#pratice 5
#求1-2+3-4+5 ... 99的所有数的和
i = 0
sum = 0
while i < 99:
i += 1
if i % 2 == 0 and i != 1:
sum -= i
else:
sum += i
print(sum)
#practice 6
#用户登入
1 i = 0
2 username = 'admin'
3 password = 'admin123'
4
5 while i < 3:
6 pw = input('请输入密码：')
7 if pw == password:
8 print('登入成功')
9 break
10 else:
11 print("输入有误，请重新输入")
12 i += 1
13 continue
14 if i == 3:
15 print("用户已被锁定")
# 计算 1 - 2 + 3 ... + 99 中除了88以外所有数的总和
1 # i = 0
2 # sum = 0
3 # while i < 99:
4 # i += 1
5 # if i == 88:
6 # continue
7 # elif i % 2 != 0:
8 # sum += i
9 # else:
10 # sum -= i
11 #
12 # print(sum)
# 计算 1 - 2 + 3 ... -99 中除了88意外所有数的总和
1 = 0
2 j = -1
3 sum = 0
4 while i < 99:
5 i += 1
6 if i == 88:
7 continue
8 else:
9 j *= -1
10 sum += i * j
11 print(sum)
# ⽤户登陆（三次输错机会）
# 且每次输错误时显示剩余错误次数（提示：使⽤字符串格式化）
1 # ⽤户登陆（三次输错机会）
2 # 且每次输错误时显示剩余错误次数（提示：使⽤字符串格式化）
3 un = 0 # 记录帐号输错的次数
4 up = 0 # 记录密码输错的次数
5 state = True # 程序当前状态
6 username = 'admin'
7 password = '123456'
8
9 while state:
10 input_username = input("Please input your username(you still have %d times): "%(3 - un))
11 if input_username == username:
12 input_password = input("Please input your password(you still have %d times): " %(3 - up))
13 if input_password == password:
14 print('Loading successfully.')
15 else:
16 up += 1
17 if up == 3:
18 print("Your ID was locked.")
19 break
20 else:
21 print("Your password is error, please check it then input again: ")
22 else:
23 un += 1
24 if un == 3:
25 print("Your ID was locked.")
26 break
27 else:
28 print("Your username is error, please check it then input again: ")