# Annotation and Operator

## Notes

A single line comment in Python begins with #, for example:

# This is a comment. print("Hello, World!")

Multi-line comments are enclosed with three single quotation marks'', or three double quotation marks', for example:

''' This is a multi-line comment with three single quotes This is a multi-line comment with three single quotes This is a multi-line comment with three single quotes ''' print("Hello, World!")

""" This is a multi-line comment with three double quotes This is a multi-line comment with three double quotes This is a multi-line comment with three double quotes """ print("Hello, World!")

## operator

Arithmetic operator

Compare (relational) operators

Assignment Operators

Logical Operator

Bitwise Operators

member operator

Identity Operator

Operator priority

Python arithmetic operator

# + Plus

# - subtraction

# * multiplying

# / Division

# % Modeling

# * power

# // take and divide

a = 21 b = 10 c = 0 c = a + b print("1 - c The value is:", c) c = a - b print("2 - c The value is:", c) c = a * b print("3 - c The value is:", c) c = a / b print("4 - c The value is:", c) c = a % b print("5 - c The value is:", c) # Modify variables a, b, c a = 2 b = 3 c = a ** b print("6 - c The value is:", c) a = 10 b = 5 c = a // b print("7 - c The value is:", c)

The output of the above example is as follows:

The value of 1 - c is 31

The value of 2 - c is 11

The value of 3 - c is 210

The value of 4 - c is: 2.1

The value of 5 - c is: 1

The value of 6 - c is 8

The value of 7 - c is: 2

Python comparison operator

# == Equivalent to - Compare Object Equivalence

# != Not equal - Compare two objects to see if they are not equal

# > Is greater than - Return x greater than y

# <less than-returns whether x is less than y. All comparison operators return 1 for true and 0 for false. This is equivalent to the special variables True and False, respectively. Note that these variable names are capitalized.

# >= greater than or equal to - Returns whether x is greater than or equal to y.

# <= less than or equal to - Returns whether x is less than or equal to y.

a = 21 b = 10 c = 0 if ( a == b ): print ("1 - a Be equal to b") else: print ("1 - a Not equal to b") if ( a != b ): print ("2 - a Not equal to b") else: print ("2 - a Be equal to b") if ( a < b ): print ("3 - a less than b") else: print ("3 - a Greater than or equal to b") if ( a > b ): print ("4 - a greater than b") else: print ("4 - a Less than or equal to b") # Modify the values of variables a and b a = 5; b = 20; if ( a <= b ): print ("5 - a Less than or equal to b") else: print ("5 - a greater than b") if ( b >= a ): print ("6 - b Greater than or equal to a") else: print ("6 - b less than a")

The output of the above example is as follows:

1 - a is not equal to b

2 - a is not equal to b

3 - a greater than or equal to b

4 - a is greater than b

5 - a is less than or equal to b

6 - b greater than or equal to a

Python assignment operator

# = A simple assignment operator c = a + b assigns the result of a + b to C

# += The addition assignment operator c += a is equivalent to c = c + a

# -= The subtraction assignment operator c -= a is equivalent to c = c - a

# *= Multiplication assignment operator c*= A is equivalent to C = c* a

# /= The division assignment operator c/= A is equivalent to c = c / a

# %= The modular assignment operator c% = a is equivalent to C = c% = a

# **= Power assignment operator c**= A is equivalent to C = c** a

# //= The integer division assignment operator c /= A is equivalent to c = c // a

a = 21 b = 10 c = 0 c = a + b print ("1 - c The value is:", c) c += a print ("2 - c The value is:", c) c *= a print ("3 - c The value is:", c) c /= a print ("4 - c The value is:", c) c = 2 c %= a print ("5 - c The value is:", c) c **= a print ("6 - c The value is:", c) c //= a print ("7 - c The value is:", c)

The output of the above example is as follows:

The value of 1 - c is 31

The value of 2 - c is 52

The value of 3 - c is: 1092

The value of 4 - c is 52.0

The value of 5 - c is: 2

The value of 6 - c is 2097 152

7 - c: 99864

Python logical operator

# x and y Boolean "and" - If x is False, x and y returns False, otherwise it returns the calculated value of y. (a and b) Return 20.

# Or x or y Boolean "or" - If x is True, it returns the value of x, otherwise it returns the calculated value of y. (a or b) Return 10.

# not x Boolean "non" - If x is True, return False. If x is False, it returns True. not(a and b) returns to False

a = 10 b = 20 if ( a and b ): print ("1 - variable a and b All for true") else: print ("1 - variable a and b There is an inaction. true") if ( a or b ): print ("2 - variable a and b All for true，Or one of the variables is true") else: print ("2 - variable a and b None of them can do it. true") # Modify the value of variable a a = 0 if ( a and b ): print ("3 - variable a and b All for true") else: print ("3 - variable a and b There is an inaction. true") if ( a or b ): print ("4 - variable a and b All for true，Or one of the variables is true") else: print ("4 - variable a and b None of them can do it. true") if not( a and b ): print ("5 - variable a and b All for false，Or one of the variables is false") else: print ("5 - variable a and b All for true")

The output of the above example is as follows:

1 - Variables a and b are true

2 - Variables a and b are true, or one of them is true

3 - Variables a and b have one not true

4 - Variables a and b are true, or one of them is true

5 - Variables a and b are false, or one of them is false

Python member operator

# In. Returns True if a value is found in the specified sequence, or False. X is in the y sequence, if x returns True in the y sequence.

# Not in returns True if no value is found in the specified sequence, or False. X is not in the y sequence, if x is not in the y sequence, return True.

a = 10 b = 20 list = [1, 2, 3, 4, 5 ]; if ( a in list ): print ("1 - variable a In a given list list in") else: print ("1 - variable a Not in the given list list in") if ( b not in list ): print ("2 - variable b Not in the given list list in") else: print ("2 - variable b In a given list list in") # Modify the value of variable a a = 2 if ( a in list ): print ("3 - variable a In a given list list in") else: print ("3 - variable a Not in the given list list in")

The output of the above example is as follows:

1 - Variable a is not in the list in the given list

2 - Variable b is not in a given list

3 - Variable a in a given list

Python identity operator

# Is to determine whether two identifiers are referenced from an object, x is y, similar to id(x) == id(y), if the same object is referenced, return True, otherwise return False

# It is not to determine whether two identifiers are referenced from different objects, similar to ID (a)!= ID (b). If the reference is not the same object, the result True is returned, otherwise False is returned.

a = 20 b = 20 if ( a is b ): print ("1 - a and b Have the same logo") else: print ("1 - a and b No identical identification") if ( id(a) == id(b) ): print ("2 - a and b Have the same logo") else: print ("2 - a and b No identical identification") # Modify the value of variable b b = 30 if ( a is b ): print ("3 - a and b Have the same logo") else: print ("3 - a and b No identical identification") if ( a is not b ): print ("4 - a and b No identical identification") else: print ("4 - a and b Have the same logo")

The output of the above example is as follows:

1 - a and b have identical identities

2 - a and b have identical identities

3 - a and b do not have the same identification

4 - a and b do not have the same identification

Python Operator Priority

The following table lists all operators from the highest to the lowest priority:

# ** Index (highest priority)

# ~+- Bit-by-bit flip, one dollar plus and minus (the last two methods are called +@and-@)

# */%// Multiplication, division, modularization and division

# +- Addition and subtraction

# "< < Right Shift, Left Shift Operator

# & bit `AND'

# ^| Bit Operator

# <= < >= comparison operator

# <>==!= equal to operator

# =%=/=//=-=+=*= **= assignment operator

# Is not an identity operator

# in not in member operator

# not and or logical operators

a = 20 b = 10 c = 15 d = 5 e = 0 e = (a + b) * c / d #( 30 * 15 ) / 5 print ("(a + b) * c / d The results are as follows:", e) e = ((a + b) * c) / d # (30 * 15 ) / 5 print ("((a + b) * c) / d The results are as follows:", e) e = (a + b) * (c / d); # (30) * (15/5) print ("(a + b) * (c / d) The results are as follows:", e) e = a + (b * c) / d; # 20 + (150/5) print ("a + (b * c) / d The results are as follows:", e)

The output of the above example is as follows:

(a + b) * c / d operation results are: 90.0

((a + b) * c) / d operation results are: 90.0

(a + b) * (c / d) operation results are: 90.0

The result of a + (b * c) / d operation is: 50.0