Basic grammar
·Single line note
Start with #
example:
#Output Picchu
print ("Pikachu")
·Multiline comment
Start with three quotation marks and end with three quotation marks
"""
"""
example
"""
output
"""
·Identifiers and keywords
Identifier: alphanumeric and underscore. It can only start with a letter or underscore
variable
-
Object has type
-
Variables are untyped, and variables are just references
a=10 print(a=10)
Operation results:
Traceback (most recent call last):
File "D:/PycharmProjects/pythonprj1/test2.py", line 5, in
print(a=10)
TypeError: 'a' is an invalid keyword argument for print()
Process finished with exit code 1
a=10 print(a==10)
Operation results
True
- Integers and strings are cached in python,
Numbers and strings in python have been created and cannot be modified
Comparison of variables
"= =" and "is"
• comparison of variables "= =" and "is"
• = =: whether the values of the data stored by the comparison object are equal;
• is: compare whether both variables refer to the same object.
•
data type
-
Number type numbers
Integer int (including Boolean bool)
Floating point float
complex type
-
String type str
-
List type list
-
Tuple type tuple
-
Set type set
-
Dictionary type dict
integer
#Express binary 0b or 0b a=0b110 print(a) b=(0B1010) print(b) #Express octal 0o or 0o c=0o123 print(c) #Express hex 0x or 0x d=0xABC print(d) #Execute the shortcut key shift+F10 now
-
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• binary, preceded by: 0b or 0b (composed of 1 and 0, enter 1 every 2);
• octal, preceded by: 0o or 0o; (composed of 0 ~ 7, 1 for every 8)
• hexadecimal, preceded by: 0x or 0x. (09. AF composition, 1 in every 16)
a=10 #bin(), oct(),hex() are built-in functions # Decimal to binary b=bin(a) #Decimal to octal c=oct(a) #Decimal to hexadecimal d=hex(a) print(a,b,c,d)
Operation results
10 0b1010 0o12 0xa
#Take a part of it from the second index position to the end, and the name is "slice" print(a,b[2:],c[2:],d[2:])
Operation results:
10 1010 12 a
#Can calculate and output large numbers intData=2013477777777777777777777777777777777777777777777777777777777777776452754264265625626572 #"m**n" is the nth power of m intData=2**111 print(intData)
Operation results:
27817953874931422193200157252797783625799553985162128378849682836025612139606873061796642986409084093027488282529479441356879309912545136580926563006055687622422043646784287399491305767249266136610482504757705065498211196461322151021271625793951908619828755931791767521474322440333549820076334848895352132541368625047123052020050690048
float
f1=1.23828475 print(f1) #int() can be used to represent the integer part, and will not be rounded, truncated and rounded. If you want to round and add 0.5 d1=int(f1) print(d1)
Operation results:
1.23828475
1
#Integer to decimal f2=float(d1) print(f2)
Operation results
1.0
Plural form
#Complex complex c1=1+2j print(c1) c2=complex(1,1) print(c2)
Operation results:
(1+2j)
(1+1j)
#Addition, subtraction, multiplication and division of complex numbers print(c1+c2) print(c1-c2) print(c1*c2) print(c1/c2)
Operation results
(2+3j)
1j
(-1+3j)
(1.5+0.5j)
#Print real part and imaginary part print(c1.real) print(c1.imag) #Print conjugate complex print(c1.conjugate())
Operation results
1.0
2.0
(1-2j)
# c3=-1j print(c3) c4=1j print(c4)
Operation results
(-0-1j)
1j
b1=True b2=False print(b1,b2) #True defaults to 1 and FALSE defaults to 0 b3=b1+1 print(b3)
Operation results
True False
2
#Bool - > int - > float - > complex conversion print(1+False) print(False-1.273+100) print(False+True+100+1+2j)
Operation results
(102+2j)
Each python object has a Boolean value**
#bool print(bool(None)) #integer print(bool(0)) #float print(bool(0.0)) #Plural form print(bool(0+0j)) #Boolean print(bool(False)) #Empty list print(bool([])) #An empty dictionary can only express an empty data print(bool({})) #tuple print(bool(())) #Empty set print(bool('')) print(bool(""))
Operation results
False
False
False
False
False
False
False
False
False
False
• built in function type(): detect different types of data.
• built in function isinstance(): judge whether the data belongs to a certain type.
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, FALSE, the default is 0
b3=b1+1
print(b3)
Operation results True False 2
#Bool - > int - > float - > complex conversion
print(1+False)
print(False-1.273+100)
print(False+True+100+1+2j)
Operation results (102+2j) **every last python Objects have a Boolean value****
#bool
print(bool(None))
#Integer
print(bool(0))
#Floating point type
print(bool(0.0))
#Plural form
print(bool(0+0j))
#Boolean
print(bool(False))
#Empty list
print(bool([]))
#An empty dictionary can only express an empty data
print(bool({}))
#Tuple
print(bool(()))
#Empty set
print(bool(''))
print(bool(""))
Operation results False False False False False False False False False False •Built in function type(): For different types of data**testing**. •Built in function isinstance(): **judge**Whether the data belongs to a certain type. [External chain picture transfer...(img-gVA5Ro6b-1631108974852)]