python数据类型

致敬hello world!

print("hello world!")

print("hello again")

print("this is the 3rd line, \n",

        "and this is also the 3rd line")

print("this is the 3rd line, \

         and this is also the 3rd line")

expression-> number

operator _> +-*/

print(4-5)

print(8+)

110/12.97

naming

number_of_cars = 34

x = 8  if x < 7:

　　print(x)

if(x < 7):

print("x is smaller than 7")

Semantics

x = 8 

if x < 7:

　　print("x is smaller tahn 7")

　　print("x is bigger than 7")

variable names, and objects

variable and value

speed_of_liuxiang = 110/12.97

distance = 1000

time = distance/speed_of_liuxiang

print(time)

print(time/60)

assign new value, Mutable

speed_of_ydj= 110/10

time = distance/speed_of_ydj

print(time)

time = time -1

print(time)

data type

interger   + - * / % //   how big is an int?    0b10 0o10 ox10

float   98.5  type(a)     import math   math.pi math.e math.floor(98.6)  math.ceil(98.6) math.pow(2,3)  math.sqrt(25)

Boolean    1 < 2    (2< 1) or(1<2)   not(2<1)    type(a)

Strings  s = 'this is a string'  type(s)   print(s)   ‘’‘this is the first line

　　　　this is the second line’‘’

type  conversions

a = str(98.6)

a

type(a)

float('98.6')

int('-123')

1 + 2.0 

True + 3

3.88 +"28"

 

combine & duplicate

template = "my name is "

name = "ydj"

greeting = template + '' " + name+" ."

print(greeting)