python代码进一步学习

Posted 2022-11-29 hjl123

1、变量的三大类型

import time

list1 = [‘tank‘, ‘jason‘]

# print(‘18岁的tank，是真的。‘)
# type
print(type(list1))

# id
print(id(list1))
# 4648825800
# 4620657608

time.sleep(5)
print(‘程序结束，list1被销毁‘)



# 可变与不可变
# 当数据修改时，id不变称之为可变类型，否则称之为不可变类型。（默写）
# 可变
list1 = [‘tank‘, ‘jason‘]
print(‘list1修改前ID：‘, id(list1))
list1.append(‘徐峰‘)   # [‘tank‘, ‘jason‘].append(徐峰）
print(list1)
print(‘list1修改后ID：‘, id(list1))

# 不可变：元组
tuple1 = (1, 2, 3)
print(id(tuple1))
print(type(tuple1))
tuple1 = (2, 3, 4)
print(id(tuple1))

 

2、用户与程序交互

‘‘‘
用户与程序交互：
     input()  输入
     print()  输出
username = input(‘请输入提示信息:‘)
‘‘‘
username = input(‘请输入用户名:‘)
print(username)
password = input(‘请输入密码:‘)
print(password)

# 如果
# username == ‘tank‘ True
# and: 左右两边的条件都为True才为True，否则为False
# password == ‘123‘ True
# if 条件判断：如果条件判断 == True, 执行if下的代码
if username == ‘tank‘ and password == ‘123‘:    # False and True  --->  False
    print(‘登陆成功‘)
else:
    print(‘登录失败‘)

 

 

3、格式化输出

# 占位符：%s
str1 = ‘很帅‘
print(‘tank%s‘ % (str1,))  #tank很帅


str2 = ‘信念与我同在，我将无坚不摧！‘

print(‘自信养成记1: %s‘ % (str2,))


price1 = input(‘请输入该用户当月扣费月租：‘)
all = input(‘请输入该用户当前余额：‘)

print(‘亲爱的移动用户，您当月月租为[%s]元，账户余额为[%s]元！‘ % (price1,all))

 

 

4、基本运算符

# 算术运算符
print(1 + 1)  
n1 = 1
# n1 = n1 + 1  # n1 += 1
# print(n1)  
n1 += 1


# 赋值运算符：-=
print(10 - 1)  

# *=
print(12 * 12)  
print(11 / 3)  
print(11 // 3)  
print(11 % 3)   


# 比较运算符
print(1 == 2)  
print(1 > 2) 
print(1 < 2)   
print(1 >= 2)  
print(1 <= 2)  

# is:比较两个变量的id是否相等
x = 10
print(id(x) == id(x))  
print(x is x)  


# 逻辑运算符
# and：左右两边的条件都为了True才为True，否则为False
print(x == 1 and x == 10) 
print(x == 10 and x == 10)  

# or：判断两边的条件是否成立，其1成立则为True
print(x == 10 or x == 1)   

# not：取反
print(x == 10)  
print(not x == 10) 

# no-->and-->or
#           True or False
print(not x == 1 or x == 10 and x == 20)  


# 链式赋值
n = 10
y = n
z = y
print(n, y, z)


# 交叉赋值
x = 10
y = 20
# x与y的值互换
# x = 20   y = 10
z = x  # 10
x = y  # 20
y = z  # 10

x = 10
y = 20
# 10, 20 = y=10, x=20
x, y = y, x
print(x, y)  


# 解压缩赋值
#       0  1  2
list1 = [1, 2, 3]
x = list1[0]
y = list1[1]
z = list1[2]
print(x, y, z)  
x, y, z = list1
print(x, y, z)  

 

 

5、流程控制

‘‘‘
if 分支
‘‘‘

# 猜字符游戏：猜测用户输入的字符是否是9527。

number = 9527

guess = input(‘请输入猜测数字：‘)

print(guess)
print(type(guess))  # str

# 把字符串类型转为整型
guess = int(guess)

print(type(guess))  #int

if guess == number:
    print(‘猜对了!‘)

elif guess < number:
    print(‘猜小了‘)

else:
    print(‘猜大了!‘)

‘‘‘
while循环：
     语法:
          while 判断条件：
          
               # 若条件成立则“循环”执行以下代码
               print(‘111‘)
               
               break：结束本层循环
‘‘‘
# import time
# while True:
#     print(11111)
#     time.sleep(1)
#     break



# 猜字符游戏： 猜测用户输入的字符是否是9527，限制只能猜3次。
number = 9527
init = 1  # 1 2 3 4
while True:    # 若init大于3结束循环
    if init > 3:
        print(‘猜错3次了，gun吧!‘)
        break

    guess = input(‘请输入猜测数字：‘)
    guess = int(guess)

    if guess == number:
        print(‘猜对了!‘)
        break

    elif guess < number:
        print(‘猜小了‘)

    else:
        print(‘猜大了!‘)

    # 若没有退出循环证明猜错了，init+1
    init += 1



#        0  1  2  3  4
# list1 = [1, 2, 3, 4, 5]
‘‘‘
需求: 
    循环取出列表list1的每一个值。

for循环:
    for x in 需要循环的值:

    for x in list1:  # x=1, x=2, x=3, x=4, x=5
        print(x)

‘‘‘
list1 = [1, 2, 3, 4, 5]
# list1_len = len(list)   # 5

# while list1_len > 0:
#     list1_len -= 1
#     # print(list1_len)  # 4 3 2 1 0

#     print(list1[list1_len])

# 依次循环取出list1中的每一个值
for x in list1:
    print(x)