Arithmetic comparison
(1) Arithmetic operator: + - * / / /%**
+
var1 = 7 var2 = 90 res = var1 + var2 print(res)
-
var1 = 7 var2 = 90 res = var1 - var2 print(res)
*
var1 = 7 var2 = 10 res = var1 * var2 print(res)
/ (the result is always decimal)
var1 = 10 var2 = 5 res = var1 / var2 print(res , type(res))
//Floor except
Divisor ÷ divisor = quotient
Note: if the divisor or divisor is a decimal, after the normal result is obtained, the value followed by. 0 becomes a decimal
var1 = 10.0 var2 = 3.0 # var2 = 3.0 res = var1 // var2 print(res)
% remainder
var1 = 7 var2 = 4 res = var1 % var2 res = -7 % 4 # -3 + 4 = 1 res = 7 % -4 # 3 + (-4) = -1 res = -7 % -4 # -3 (divisor and divisor are both negative, normal result plus minus sign) res = 81 % 7 # 4 res = 81 % -7 # -3 res = -81 % 7 # 3 res = -81 % -7 # -4 print(res)
**Power operation
res = 2 ** 3 print(res)
(2) Comparison operators: >, <, > =, > =, = ==
The result of the comparison operator is either True or False. There are only two values
res = 10 > 5 res = 10 >= 10 # ==This symbol is used to compare whether the values on both sides of = = are the same res = 5 == 9 res = 5 != 9 print(res)
(3) Assignment operator: = + = - = * = / = / / / =% =**=
=The assignment operator assigns the value on the right to the variable on the left
a = 5 <= 3 print(a) var1 = 10 var2 = 5
+=
"""var1 = var1 + var2""" # var1 += var2 # print(var1)
-=
"""var1 = var1 - var2""" # var1 -= var2 # print(var1)
%=
"""var1 = var1 % var2""" var1 %= var2 print(var1)
(4) Member operators: in and not in (for container data)
① When judging a string, it must be a continuous fragment
strvar = "It's going to rain today,Hurry home and collect your clothes" res = "this" in strvar res = "weather" in strvar res = "hurry back" in strvar print(res)
② For lists, tuples, collections
container = ["Shenyang Zhao","Zhao Wanli","Zhao Shichao"]
container = ("Shenyang Zhao","Zhao Wanli","Zhao Shichao")
container = {"Shenyang Zhao","Zhao Wanli","Zhao Shichao"}
# res = "Zhao Shenyang" in container
# res = "Zhao Wanli" not in container
res = "Zhao Shichao 1223232" not in container
print(res)
③ For the dictionary (the key of the dictionary is judged, not the value)
container = {"zsy":"Shenyang Zhao","zwl":"Zhao Wanli","zsc":"Zhao Shichao"}
res = "Shenyang Zhao" in container # False
res = "zsy" in container
print(res)
(5) Identity operators is and is not (detect whether the two data are the same value in memory)
① Integer - 5 ~ positive infinity
var1 = 100 var2 = 100 print(var1 is var2)
② Floating point nonnegative number
var1 = -9.1 var2 = -9.1 print(var1 is var2)
③ bool is the same
var1 = True var2 = True print(var1 is var2)
④ complex is different between real number and imaginary number (except for imaginary number)
var1 = 6-8j var2 = 6-8j var1 = -10j var2 = -10j print(var1 is var2)
⑥ Container: the same string and empty tuple can be the same. All the remaining containers are different
container1 = () container2 = () print(container1 is not container2) container1 = "you" container2 = "you" print(container1 is not container2) container1 = [1,23,3] container2 = [1,23,3] print(container1 is not container2)
(6) Logical operator: and or not
① And logic and
One truth is true, one false is false
res = True and True # True res = True and False # False res = False and True # False res = False and False # False print(res)
② or logic
One true is true, and all false is false
res = True or True # True res = False or True # True res = True or False # True res = False or False # False print(res)
③ not logical
res = not True res = not False print(res)
④ Logic short circuit
No matter whether the following expression is True or False, the final result cannot be changed. Then, short circuit directly and the following code will not be executed;
(1) True or print("program executed ~ 1111")
(2) False ande print("program executed ~ 2222")
True or print("The program was executed ~ 1111")
True or True => True
True or False => True
False and print("The program was executed ~ 2222")
False and True => False
False and False => False
Calculation rule:
First, brain compensation is used to calculate whether the Boolean value of the current expression is True or False. If there is a True or expression or a False and expression, it will be returned directly. The following code will not be executed. If there is no short-circuit effect, it will be returned directly to the latter
res = 5 and 6 # 6
'''
True and True => True
True and False => False
'''
Next, let's look at a piece of code
res = 5 or 6 # 5 res = 0 and 999 res = 0 or "abc" print(res)
Priority of logical operators:
Priority from high to low: () > not > and > or
Small exercise:
res = 5 or 6 and 7 # 5 or 7 => 5 res = (5 or 6) and 7 # 5 and 7 res = not (5 or 6) and 7 # not 5 and 7 => False and 7 => False res = 1<2 or 3>4 and 5<100 or 100<200 and not (700>800 or 1<-1)
not (False or False) => True res = 1<2 or 3>4 and 5<100 or 100<200 and not (700>800 or 1<-1) res = True or False and True or True and True res = True or False or True res = True or True => True print(res)
(7) Bitwise operators: & ^ < > >~
① & bitwise AND
var1 = 19 var2 = 15 res = var1 & var2 print(res)
#The result is this: """ 000 ... 10011 000 ... 01111 000 ... 00011 => 3 """
② | bitwise OR
var1 = 19 var2 = 15 res = var1 |var2 print(res)
The result is this: """ 000 ... 10011 000 ... 01111 000 ... 11111 """
③ ^ bitwise XOR
Different quantity = > true; otherwise, False is returned
var1 = 19 var2 = 15 res = var1 ^ var2 print(res)
The result is this: """ 000 ... 10011 000 ... 01111 000 ... 11100 """
④ < < shift left (want to be in multiplication)
This number is multiplied by the n-th power of 2
res = 5 << 1 # 10 res = 5 << 2 # 20 res = 5 << 3 # 40 print(res)
The result is this:
"""
000 ... 101 => 5
000 .. 1010 => 10
000 ..10100 => 20
000 .101000 => 40
"""
⑤ > > shift right (equivalent to Division)
This number is divided by 2 to the nth power
res = 5 >> 1 # 2 res = 5 >> 2 # 1 res = 5 >> 3 # 0
print(res)
The result is this:
"""
000 ... 101
000 ... 010 => 2
000 ... 001 => 1
000 ... 000 => 0
"""
⑥ ~ bitwise non (for complement operation, bitwise inversion, including each bit)
-(n+1)
Exercise 1:
# res = ~22 res = ~19 print(res)
The result is this: ""“
Original code: 000 ten thousand and eleven
Inverse code: 000 ten thousand and eleven
Complement: 000 ten thousand and eleven
Complement: 000 ten thousand and eleven
Bitwise non: 111 01100
Give you the complement - > original code
Complement: 111 01100
Inverse code: 100 ten thousand and eleven
Original code: 100 10100 => -20
"""
Exercise 2
res = ~-19 print(res)
The result is this:
"""
Original code: 100 ten thousand and eleven
Inverse code: 111 01100
Complement: 111 01101
Complement: 111 01101
Bitwise non: 000 ten thousand and ten
Give you the complement - > original code (because it is an integer, the original inverse complement is the same)
000 ... 10010 => 19
"""
Summary:
Individual operators:
The highest operator is:**
Operator with the lowest priority:=
() can raise priority
Unary operators > binary operators (priority)
Unary operator: operate on a value at the same time ~-
Binary operator: at the same time, operate on a value + - * /
Operators of the same kind:
Arithmetic operators: multiply and divide > add and subtract
Logical operators: () > not > and > or
Bitwise operators: (< > >) > & > ^ >|
Overall sorting:
Arithmetic operators > bit operators > comparison operators > identity operators > member operators > logical operators
The assignment operator is used for closing
Little practice
res = 5+5 << 6 // 3 is 40 and False """ res = 10 << 2 is 40 and False res = 40 is 40 and False res = True and False res = False """ print(res) # Raise the next priority with parentheses res = (5+5) << (6//3) is 40 and False