# Python Operator

## What is an operator?

This section mainly describes the Python operators. For a simple example 4 +5 = 9 . In the example, 4 and 5 are called operands, and "+" are called operators.

The Python language supports the following types of operators:

Next let's learn Python operators one by one.

## Python Arithmetic Operator

The following hypothetical variables: a=10, b=20:

OperatorDescriptionInstance
+Plus - Add two objects a + b Output 30
-minus - get a negative number or a number minus another number a - b output result -10
*multiply - multiply two numbers or return a string that is repeated several times a * b output result 200
/Division - x divided by y b / a Output 2
% modulo - returns the remainder of the division b % a output 0
**power - returns the power of y of x a**b is the 20th power of 10, and the output is 100000000000000000000
//Division - Returns the integer part of the quotient (round down)
```>>> 9//2
4
>>> -9//2
-5```

The following example demonstrates the operation of all Python arithmetic operators:

## Instance(Python 2.0+)

#!/usr/bin/python # -*- coding: UTF-8 -*- a = 21 b = 10 c = 0 c = a + b print "1 - c Value：", c c = a - b print "2 - c Value：", c c = a * b print "3 - c Value：", c c = a / b print "4 - c Value：", c c = a % b print "5 - c Value：", c # Modify variable a 、b 、c a = 2 b = 3 c = a**b print "6 - c Value：", c a = 10 b = 5 c = a//b print "7 - c Value：", c

The above example output：

```1 - c Value： 31
2 - c Value： 11
3 - c Value： 210
4 - c Value： 2
5 - c Value： 1
6 - c Value： 8
7 - c Value： 2```

note：Python2.x ，Integers divide an integer and only get an integer. If you want to get the fractional part, change one of them to a floating point number.

## Python comparison operator

The following hypothesis variable a is 10 and variable b is 20:

OperatorDescriptionInstance
== is equal to - compare objects are equal (a == b) returns False.
!= Not equal to - Compare two objects are not equal (a != b) Returns true.
<>Not equal to - Compare two objects are not equal (a <> b) Returns true. This operator is similar to != .
> Greater than - Returns whether x is greater than y (a > b) Returns False.
< 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. (a < b) returns true.
>= Greater than or equal to - Returns whether x is greater than or equal to y. (a >= b) returns False.
<= Less than or equal to - Returns whether x is less than or equal to y. (a <= b) returns true.

The following example demonstrates the operation of all Python comparison operators:

The following example demonstrates the operation of all Python comparison operators.：

## Instance(Python 2.0+)

#!/usr/bin/python # -*- coding: UTF-8 -*- a = 21 b = 10 c = 0 if a == b : print "1 - a equal b" else: print "1 - a not equal to b" if a != b : print "2 - a not equal to b" else: print "2 - a equal b" if a <> b : print "3 - a not equal to b" else: print "3 - a equal b" if a < b : print "4 - a Less than b" else: print "4 - a greater or equal to b" if a > b : print "5 - a more than the b" else: print "5 - a Less than or equal to b" # Modify the values of variables a and b a = 5 b = 20 if a <= b : print "6 - a Less than or equal to b" else: print "6 - a more than the b" if b >= a : print "7 - b greater or equal to a" else: print "7 - b Less than a"

The above example output：

```1 - a not equal to b
2 - a not equal to b
3 - a not equal to b
4 - a greater or equal to b
5 - a more than the b
6 - a Less than or equal to b
7 - b greater or equal to a```

## Python assignment operator

The following hypothesis variable a is 10，The variable b is 20：

OperatorDescriptionInstance
=Simple assignment operator c = a + b Assign the result of a + b to c
+=Additional Assignment Operator c += a is equivalent to c = c + a
-=Subtraction assignment operator c -= a is equivalent to c = c - a
*=Multiplication assignment operator c *= a is equivalent to c = c * a
/=Division assignment operator c /= a is equivalent to c = c / a
%=Modification Assignment Operator c %= a Equivalent to c = c % a
**=Power assignment operator c **= a is equivalent to c = c ** a
//= Rounding the assignment operator c //= a is equivalent to c = c // a

The following example demonstrates the operation of all Python assignment operators:

The output of the above example:

```1 - c Value： 31
2 - c Value： 52
3 - c Value： 1092
4 - c Value： 52
5 - c Value： 2
6 - c Value： 2097152
7 - c Value： 99864```

## Python Bit operator

The bitwise operator is calculated by treating the number as a binary. The bitwise algorithm in Python is as follows:

In the table below, the variable a is 60 and b is 13. The binary format is as follows:

```a = 0011 1100

b = 0000 1101

-----------------

a&b = 0000 1100

a|b = 0011 1101

a^b = 0011 0001

~a = 1100 0011```
< Td> (a & b) output 12, binary interpretation: 0000 1100
OperatorDescriptionInstance
&Bitwise AND Operator: Two values ​​participating in the operation. If both corresponding bits are 1, the result of this bit is 1, otherwise 0
| Bitwise OR Operator: As long as one of the corresponding two binary digits is 1, the result bit is 1. (a | b) Output 61, binary interpretation: 0011 1101
^bitwise XOR operator: When the two corresponding binary digits are different, the result is 1 (a ^ b) Output 49, binary interpretation: 0011 0001
~ Bitwise inversion operator: Inverts each binary bit of data, that is, changes 1 to 0 and 0 to 1. ~x is similar to -x-1 (~a ) output -61 , binary interpretation : 1100 0011, in the complement form of a signed binary number.
<<Left move operator: Each binary of the operand is shifted left by several bits, to the right of <<<<>> The number specifies the number of bits to move, the high bit is discarded, and the low bit is zero. a << 2 output 240, binary interpretation: 1111 0000
>>Right Move Operator: Shifts each binary of the operand to the left of ">>" to the right by several bits, > > The number on the right specifies the number of bits moved a >> 2 Output 15 , Binary Explanation: 0000 1111

The following example demonstrates the operation of all Python bitwise operators:

## Instance(Python 2.0+)

#!/usr/bin/python # -*- coding: UTF-8 -*- a = 60 # 60 = 0011 1100 b = 13 # 13 = 0000 1101 c = 0 c = a & b; # 12 = 0000 1100 print "1 - c Value：", c c = a | b; # 61 = 0011 1101 print "2 - c Value：", c c = a ^ b; # 49 = 0011 0001 print "3 - c Value：", c c = ~a; # -61 = 1100 0011 print "4 - c Value：", c c = a << 2; # 240 = 1111 0000 print "5 - c Value：", c c = a >> 2; # 15 = 0000 1111 print "6 - c Value：", c

The output of the above example:

The Python language supports logical operators. The following assumes that the variable a is 10 and b is 20:

OperatorLogical ExpressionDescriptionInstance
andx and y Boolean "and" - If x is False, x and y return False, otherwise it returns the calculated value of y. (a and b) returns 20.
orx or yBoolean "or" - If x is nonzero, it returns the value of x, otherwise it returns the computed value of y. (a or b) returns 10.
notnot xBoolean "Non" - Returns 0 if x is True. If x is False, it returns True. not(a and b) returns False

The output of the above example:

## Instance (Python 2.0+)

variable a And b are both true" else: print "1 - variable a with b Have one not true" if a or b : print "2 - variable a with b All for true，Or one of the variables is true" else: print "2 - variable a with b Not for true" # Modify variable a Value a = 0 if a and b : print "3 - variable a with b Not for true" else: print "3 - variable a with b Have one not true" if a or b : print "4 - variable a with b All for true, or one of the variables istrue" else: print "4 - variable a with b Not for true" if not( a and b ): print "5 - variable a with b All for false，Or one of the variables isfalse" else: print "5 - variable

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