python comments pytho good programmer does not have to pursue short code, code readability is crucial
to interact with users
convert input input will enter the contents into a string
output print
formatted output% d% s account % d placeholder only integer, representing first come first unlabeled
python basic data types
int integer
float float
str string
list listing
dict dictionary
bool Boolean
operators
basic operators + - * / =
logical operators = =! IS =
Python comments in
what is NOTE: code explanation or comment, the comment only posters, Python is not recognized
annotation classification:
1. single-line comment #
2. Three marks (which may be single or may be three three pairs) '' '
multi-line comment
' ''
"" "
multi-line comment
" ""
input
1.python3 the input
keyword: input ()
python3 the input acquired user input saved as a unified whole string type
input 2.python2 in
1.input ()
you need to tell people what you typed input data type
>>> name = INPUT ( 'INPUT >>> Please:')
Please >>> INPUT: Jason
Traceback (MOST Recent Last Call):
File "<stdin>", Line. 1, in <Module1>
File "<String > ", Line. 1, in <Module1>
NameError: name 'Jason' IS Not defined
>>> name = INPUT ( 'INPUT >>> Please:')
Please >>> INPUT: 'Egon'
>>> name
'egon'
>>> type(name)
<type 'STR'>
>>> name = INPUT ( 'INPUT >>> Please:')
Please >>> INPUT: [1,2,3,4]
>>> name
[. 1, 2,. 3,. 4]
type >>> (name)
<type 'List'>
2.raw_input ()
data entered by the user will raw_input python2 unified also stored as a string
>>> name1 = raw_input ( '>>>>>>> >>>>>>>>>>>: ')
>>>>>>>>>>>>>>>>>>: Jason
>>> NAME1
' Jason '
>>>type(name1)
<type 'str'>
>>> name1 = raw_input('>>>>>>>>>>>>>>>>>>:')
>>>>>>>>>>>>>>>>>>:[1,2,3,4,5]
NAME1 >>>
'[1,2,3,4,5]'
>>> type (NAME1)
<type 'STR'>
: The User input is uniform string
of code changes once, you must be repeated below changes py file
otherwise, or you do not change the code before the program execution (******)
formatted output
```python
name=input('please input your username：')
age=input('please input your age：')
print('my name is',name,'my age is',age)
print('my name is %s，my age is %s' %(name,age))
'''
my name is 输入的用户名，my age is 输入的年龄
'''
print('my name is %s my age is %s' %(18,'egon'))
Print ( ' My name IS% S My Age IS% D ' % ( ' Egon ' , 18 is ))
Print ( ' My name IS% S My Age IS% S ' % ( ' Egon ' , 18 is ))
Print ( ' My Age% S iS My name iS S% ' % ( ' Egon ' , [l, 2,3])) # % S may receive any type of value
Print ( ' My name My Age iS iS S% D% ' % ( ' Egon ' , ' XXX ')) # % D can receive a digital type
Data Types
What is Data: Measuring / recording state of things / features
What is type: different data should have different types of storage
such as: text, video, audio. . .
int int 1,5,56,9165
a float floating-1.1,, 5.0
STR string 'of all content' used for storing annotation information
data type list list ordered list of index [0] as the first data beginning
students_info=[
['egon',18,['play',]],
['alex',18,['play','sleep']]
]
print(students_info[1][2][0])
dict Dictionary kv key-value pairs used to access k v
info={'name':'egon','sex':'male','age':18} info=dict({'name':'egon','sex':'male','age':18})
print(type(info))
print(info['name'])
d = { ' a ' : { ' it ' [1,5,9]}, ' b ' : ' vb ' , ' c ' : ' vc ' , ' d ' : ' vd ' }
print (d [ ' to ' ] [ ' it ' ] [2])
bool Boolean value determination
# Arithmetic
RES =. 1 +. 3
Print (RES)
Print (. 1 +. 3)
Print (10 /. 3) # Results decimals part
print (10 // 3) # leaving only the integer portion of the
print (10% 3) # take the remainder
Print (2 **. 3)
# comparison operation: == => <> = <=!
# knowledge of:
may compare the size between each digital #
Print (10>. 3)
Print (10> 3.1)
# string but only You can compare the size of the character string (the character corresponding to the position according to the ASCII table to compare the reference)
MSG1 = 'Hello'
Msg2 = 'Z'
Print (MSG1> Msg2)
# a-Za-Z
Print ( 'a'> 'the Z' )
Print ( 'the Z'> 'the Y')
Print (len ( 'Hello')>. 3)
Print ( 'a'>. 3)
# list can list comparison with the size (in accordance with the order corresponding to the value of the position comparison, the corresponding position value must be the same type)
L1 = [l, 2,3]
L2 = [10,]
Print (L2> L1)
L3 = [10,2, 'B',. 3]
L4 = [10,2, 'B', 'C']
Print (L3> L4)
# assignment operator
18 is = Age
# incremental assignment
Age Age + = # = Age +. 1. 1
Print (Age)
# chain assignment
X = 100
Y = X
Z X =
X = Y = Z = 100
Print (ID (X), ID ( Y), ID (Z))
# intersecting assignment
m = 1000
n-= 2000
# TEMP = m
# m = n-
# n-= TEMP
n-, m = m, n-
Print (m, n-)
# decompression assignment
salaries = [11, 22,33,44,55,]
MON1 = ual relations [0]
MON2 = ual relations [. 1]
MON3 = ual relations [2]
MON4 = ual relations [. 3]
MON5 = ual relations [. 4]
MON1, MON2, MON3, MON4, MON5 = ual relations
Print (MON1, MON2, MON3, MON4, MON5)
# equals the number of values included in the right left operand must be consistent with the number of variable names
MON1, MON2, MON3, MON4, MON5, MON6 = ual relations
MON1, MON2 , MON3, MON4, ual relations =
_ = 3333
Print (_)
mon1, mon2, _, _, _ = salaries # underlined eventually assigned 55
MON1, MON2, * _ = ual relations
Print (MON1)
Print (MON2)
ual relations = [11,22,33,44,55,]
First = ual relations [0]
Last = ual relations [. 4]
First, _, _, _, = Last ual relations
First, * _, = Last ual relations
Print (First)
Print (Last)
`` `
### logical operations
` `` Python
Age 20 is =
Sex = 'FEMALE'
# logical operators
# and: connecting the left and right two conditions, only the final result in the case where the two conditions are true only for the True
Print (Age> 18 is and Age <26 is and Sex == 'FEMALE' . 1 and>. 3)
# or: connecting the left and right conditions, whenever a condition is established for the final result True
Print (. 1>. 3 or 2>. 4 or 'X' == 'Y' or ==. 1. 1)
# Not
Print (Not. 1>. 3)
Print (Not (. 1>. 3 or 2>. 4 or 'X' == 'Y' or ==. 1. 1))
res=(3>4 and 4>3) or (1==3 and ('x' == 'x' or 3 >3))
print(res)
```