基本运算符和if判断

基本运算符

算数运算符 比较运算符 赋值运算符 逻辑运算符 身份运算符

python运算优先级 链式赋值 交叉赋值 解压缩

x = 1
y = 2
print(x + y)
print(x - y)
print(x * y)
print(x / y)
print(x // y)# 整除
print(x ** y)# 幂 次方

3
-1
2
0.5
0
1

 

x = 1
y = 2
print(x == y)
print(x != y)
print(x > y)
print(x <= y)

False
True
False
True

 

a = 300 
print(a)
id(a)

300

 

 

73389712

 

a +=100#a=a+100
print(a)
id(a)

400

 

 

73389584

 

a *=10
print(a)
id(a)

4000

 

 

73389968

 

a /= 10#a=a/10
print(a)
id(a)

400.0

 

 

73389296

 

a //=10
print(a)
id(a)

40.0

 

 

73389568

 

逻辑运算符

and（和）/or（或）/not（否）

true and true = true true and false = flase ture or true = true true or flase = true flase or flase = flase not true = flase not flase = true

身份运算符

x = 300
y = 300
print(id(x)==id(y))

False

 

x = y =300
print(id(x)==id(y))

True

链式赋值

x = 10
y = 10
z = 10
x = y = z =10
print(x,y,z)

10 10 10

交叉赋值

x = 10
y = 20
​
z = x
x = y
y = z
print(x,y)

20 10

 

x,y=y,x
print(x,y)

20 10

解压缩赋值

nick_hobby_list = ['run','eat']
somebody_hobby_list = ['chi','he','piao','du']
hobby1 = nick_hobby_list[0]
hobby2 = nick_hobby_list[1]
print(hobby1,hobby2)

run eat

 

somebody_hobby_list = ['chi','he','piao','du']
hobby1,hobby2 = somebody_hobby_list
print(hobby1,hobby2)

---------------------------------------------------------------------------
​
ValueError                               Traceback (most recent call last)
​
<ipython-input-24-a17f049955a2> in <module>
     1 somebody_hobby_list = ['chi','he','piao','du']
----> 2 hobby1,hobby2 = somebody_hobby_list
     3 print(hobby1,hobby2)

ValueError: too many values to unpack (expected 2)

 

somebody_hobby_list= ['piao','666','233','13']
hobby1,hobby2,hobby3,hobby4 = somebody_hobby_list
print(hobby1,hobby3)

piao 233

 

NICKOFNAME = 'nick'
NICKOFNAME = 'zhouruixing'
print(NICKOFNAME)

zhouruixing

 

somebody_hobby_list= ['piao','666','233','13']
hobby1,_,hobby3,_ = somebody_hobby_list
print(hobby1,hobby3)

piao 233

 

somebody_hobby_list= ['piao','666','233','13']
hobby1,_,_,_ = somebody_hobby_list
print(hobby1)

piao

 

somebody_hobby_list= ['piao','666','233','13','chi','he','du','ni']
hobby1,*_,hobby6,_ = somebody_hobby_list
print(hobby1,hobby6)

piao du

 

if语句

编程语言：人与计算机交流的介质 编程：人操控计算机工做，让计算机干活，代替劳动力 计算机模仿人类 好比面前一条狗

1. 判断是哪一种生物-狗

2. 小奶狗仍是疯狗 3.1. 小奶狗 -上千抚摸 3.2. 疯狗-远离 人有判断能力，计算机也有判断能力 python中判断使用if语句

if 条件： 代码块 code1 code2

dog_name1 = '疯狗'
dog_name2 = '小奶狗'
​
if dog_name1 == '疯狗':
    print('远离它')

远离它

if.........else

dog_name1 = '疯狗1'
dog_name2 = '小奶狗'
​
if dog_name1 == '疯狗':
        print('y远离他')
else:
        print('抚摸它')

抚摸它

180以上全票 150-170半票 120如下免票

height = 150
if height >= 180:
    print('全票')
else:
    if height <= 120:
        print('免票')
    else:
        print('半票')

半票

 

height = input('请输入你的身高: ')
height = int(height)
​
if height >= 180:
    print('全票')
elif height <= 120:
    print('免票')
elif height >= 150 and height <= 170:
    print('半票')
else:
    print('你可能不适合我')

请输入你的身高: 155
半票

if 嵌套

height = 160
​
if height >= 180:
    print('全票')
else:
    if height <= 120:
        print('免票')
    else:
        print('你可能过高了')

你可能过高了

猜年龄

while True:
    age = input('请输入年龄： ')
    age = int(age)
    if age > 19:
        print("太长了")
    elif age == 19:
        print('bonggo')
        break
    else:
        print("过小了")

请输入年龄： 15
过小了
请输入年龄： 20
太长了
请输入年龄： 19
bonggo