1. notes * *

1.1 single line comment

# The first python annotation

1.2 Multi-line Notes

The first one
 python
 Notes' '

**

2. Specify the spacer sep**

When there is no sep, the default spacer is a space

>>> print(1,2,3)
1 2 3

You can specify spacers when there is sep
For example, sep="+" specifies the spacer as+

>>> print(1,2,3,sep="+")
1+2+3

3. line indentation *

if a>60:   #With a colon at the end, the next line is indented with a Tab key
	print("pass")

4. Data type*

4.1 figures
int - Integer
float-floating-point type
bool - Boolean (1 and 0)
4.2 String (str)

str(999)  #Will automatically convert to string'999'
str(6)*6  #This is equivalent to six replications, unlike int (6)*6.
str(6)+str(6)  #Equivalent to two characters'6'

>>> str(999)
'999'
>>> str(6)*6
'666666'
>>> str(6)+str(6)
'66'

>>> int(6)*6
36
>>> int(6)+int(6)
12

4.3 list

list1[1]  #A list of elements
list2[]  #Null list
list3[1,2,3]

4.4 tuple

t1=(1,2)
t2=(1,)  #When there is only one element in a tuple, the comma at the end cannot be dropped
t3=tuple()  #Empty ancestor

4.5 Sets

set1={1,2}
set2={1}
set3=set()  #Empty set

4.6 Dictionary (dict) - Difference from Collection: Colon in Dictionary

d1={"key1":1,"key2":2}  #The dictionary is unique and cannot be renamed. If the name is the same, the first one is read by default.
d2={1:2}
d3={}  #The dictionary is empty.

**

5. Arithmetic Operators*

5.1 Mathematical Operator
Except (/)
Dividing (//)
Balance (%)
Power (**)

>>> 2/3
0.6666666666666666
>>> 2//3
0
>>> 2%3
2
>>> 2**3   #The third power equivalent to 2
8

5.2 Comparing Operator - Return Value is Boolean
Equivalent to (==) - Distinguished from the assignment statement, it is equal to an equal sign, and assignment is a single equal sign.
Not equal to (! =)
Greater than (>)
Less than (<)
Greater than or equal to (>=)
Less than or equal to (<=)
5.3 assignment operator
5.3.1 and operation (&)

>>> bin(12)      #Binary representation of 12
'0b1100'       #The binary of 12 is 1100, and 0b in front represents binary.
>>> bin(25)
'0b11001'
>>> 12&25     #The sum operations of 12 and 25, bitwise and, are 1:00 and the rest are 0.
8
>>> bin(8)
'0b1000'

5.3.2 or operation (|)

>>> 12|25         #Or operations - bitwise or, when both are zero, 0, and the rest are 1
29
>>> bin(29)
'0b11101'

5.3.3 Non-operation (~)

>>> ~12    #Non-Operational --- Take the inverse and subtract one (12 takes the inverse as - 12, - 12-1= - 13)
-13
>>> bin(-13)
'-0b1101'

5.3.4 XOR (^)

>>> bin(12)
'0b1100'
>>> bin(25)
'0b11001'
>>> 12^25   #XOR Operations - Bit XOR, Same 0, Different 1
21
>>> bin(21)
'0b10101'

5.3.5 left shift (< <)

>>> 12<<1   #Moving one bit to the left is equivalent to multiplying 2 --- 12*2
24
>>> 12<<2      #Move two left --- 12*2*2=48
48

5.3.6 Right Shift (*)

>>> 12>>1    #To move one bit to the right is equivalent to dividing it by 2 --- 12/2 = 6
6
>>> 12>>2   #Move two to the right --- 12/2/2 = 3
3

5.4 Logic Operator
5.4.1 and -- Pre-true, returns the value behind; Pre-false, returns the value before.

>>> a=3
>>> b='pass'
>>> c=[]
>>> print(a and b)      #Front Truth, Return Back Value
pass
>>> print(c and b)      #Pre-vacation, returns the previous value
[]

5.4.2 or -- Pre-true, returns the value of the front; Pre-false, returns the value of the back

>>> a=3
>>> b='pass'
>>> c=[]
>>> print(a or b)      #Front Truth, Returns Front Value
3
>>> print(c or b)      #Pre-leave, returns the following value
pass

5.4.3 not

>>> a=3
>>> print(not a)     #It turned out to be true not and then False.
False
>>> c=[]
>>> print(not c)     #True after false not s
True

5.5 member operator
5.5.1 in

>>> 1 in [1,2,3]
True
>>> 4 in [1,2,3]
False
>>> 1 in {1:2,2:3,4:1}
True
>>> 3 in {1:2,2:3,4:1}      #Look in the dictionary for the first half
False

5.5.2 not in - Contrary to in

>>> 1 not in [1,2,3]
False
>>> 4 not in [1,2,3]
True
>>> 1 not in {1:2,2:3,4:1}
False
>>> 3 not in {1:2,2:3,4:1}
True

5.6 Identity Operator
5.6.1 is

>>> a=1
>>> b=1
>>> a is b       #Numbers are immutable types
True
>>> a=[1]
>>> b=[1]
>>> a is b      #Lists are variable types
False

5.6.2 is not -- contrary to is

>>> a=1
>>> b=1
>>> a not is b       
False
>>> a=[1]
>>> b=[1]
>>> a not is b      
True