Day02

Day02

今日内容:
    - 变量的三大特征
        type:
            查看数据的类型
        id:
            表示变量在内存中的地址，是一串数字
        value:
            变量的值

- 流程控制
    对流程的控制，控制某些事情的发生。

     - if分支判断：
         语法:
              if 判断条件：
                   # 条件若成立执行
                   print("条件成立！")

              # 若if条件不成立，则执行此处
              elif 判断条件：
                   print（"另一个条件成立"）

              # 若if条件不成立，则执行此处
              elif 判断条件：
                   print（"另一个条件成立"）

              # 若if与elif条件不成立，则执行此处else:
                   # 若条件不成立则执行
                   print（"条件不成立！"）

```
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 Ture:
#      print(11111)
#      time,sleep(1)
#      break

 

username = input ("请输入用户名：")
print(username)
password = input("请输入密码：")
print(password)

if username =="warren" and password =="666666":
    print("登陆成功")
else:
    print("登陆失败")

str = "everybaby666"

print("warren:%s" %(str,))

# - 算术运算符
print(1+1) # 2
ni = 1
# n1 = n1 + 1# n1 += 1
# print(n1) # 2
n1 = 1

# 赋值运算符： -=
print(10 - 1)  #9

# *=
print(12 * 12)  # 144
print(11/3)  # 3.666...
print(11//3)  # 3
print(11 % 3)  # 2

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

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

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

# 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)  # True

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

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

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

n = y =z = 10
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 )  # 20 10

# 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)   # 1 2 3
x, y, z = list1
print(x,y,z)  # 1 2 3

# 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

# 把字符串类型转化为整型
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!")

# 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

list1 = [1, 2, 3, 4, 5]
# list1_len = len(list1)  # 5
# while list1_len > 0:
#     list1_len -=1
#      =print(list1_[list1_len])
#  依次循环取出list1中的每一个值
for x in  list1:
    print(x)