Python Operators

What is an Operator?

This chapter mainly explains Python operators. Let's take a simple example 4 +5 = 9 In the example,4and5is calledoperand，+is called an operator.

The Python language supports the following types of operators:

• Arithmetic operators
• Comparison (relational) operators
• Assignment operators
• Logical operators
• Bitwise operators
• Membership operators
• Identity operators
• Operator precedence

Next, let's learn Python operators one by one.

Python Arithmetic Operators

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

>>> 9//2
4
>>> -9//2
-5

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

The output of the above example is:

1 - c 的值为： 31
2 - c 的值为： 11
3 - c 的值为： 210
4 - c 的值为： 2
5 - c 的值为： 1
6 - c 的值为： 8
7 - c 的值为： 2

Note:In Python 2.x, integer divided by integer can only yield an integer. If you want the fractional part, change one of the numbers to a float.

>>> 1/2
0
>>> 1.0/2
0.5
>>> 1/float(2)
0.5

Python Comparison Operators

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

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

The output of the above example is:

1 - a 不等于 b
2 - a 不等于 b
3 - a 不等于 b
4 - a 大于等于 b
5 - a 大于 b
6 - a 小于等于 b
7 - b 大于等于 a

Python Assignment Operators

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

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

The output of the above example is:

1 - c 的值为： 31
2 - c 的值为： 52
3 - c 的值为： 1092
4 - c 的值为： 52
5 - c 的值为： 2
6 - c 的值为： 2097152
7 - c 的值为： 99864

Python Bitwise Operators

Bitwise operators treat numbers as binary for calculation. The bitwise operation rules in Python are as follows:

In the table below, variable a is 60 and b is 13, with binary formats as follows:

a = 0011 1100

b = 0000 1101

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

a&b = 0000 1100

a|b = 0011 1101

a^b = 0011 0001

~a  = 1100 0011

The following example demonstrates the operations of all bitwise operators in Python:

The output of the above example is:

1 - c 的值为： 12
2 - c 的值为： 61
3 - c 的值为： 49
4 - c 的值为： -61
5 - c 的值为： 240
6 - c 的值为： 15

Python Logical Operators

Python language supports logical operators. Assume variable a is 10 and b is 20:

The output of the above example is:

The output of the above example is:

1 - 变量 a 和 b 都为 True
2 - 变量 a 和 b 都为 True，或其中一个变量为 True
3 - 变量 a 和 b 有一个不为 True
4 - 变量 a 和 b 都为 True，或其中一个变量为 True
5 - 变量 a 和 b 都为 False，或其中一个变量为 False

Python Membership Operators

In addition to the operators above, Python also supports membership operators, which test whether a sequence contains a series of members, including strings, lists, or tuples.

The following example demonstrates the operations of all membership operators in Python:

The output of the above example is:

1 - 变量 a 不在给定的列表中 list 中
2 - 变量 b 不在给定的列表中 list 中
3 - 变量 a 在给定的列表中 list 中

Python Identity Operators

Identity operators are used to compare the storage units of two objects

Note: id()The function is used to get the memory address of an object.

The following example demonstrates the operations of all identity operators in Python:

The output of the above example is:

1 - a 和 b 有相同的标识
2 - a 和 b 有相同的标识
3 - a 和 b 没有相同的标识
4 - a 和 b 没有相同的标识

Difference between is and ==:

is is used to determine whether two variable references refer to the same object (the same memory space), == is used to determine whether the values of the referenced variables are equal.

>>> a = [1, 2, 3]
>>> b = a
>>> b is a 
True
>>> b == a
True
>>> b = a[:]
>>> b is a
False
>>> b == a
True

Python Operator Precedence

The following table lists all operators from highest to lowest precedence:

The following example demonstrates the operations of all operator precedence in Python:

The output of the above example is:

(a + b) * c / d 运算结果为： 90
((a + b) * c) / d 运算结果为： 90
(a + b) * (c / d) 运算结果为： 90
a + (b * c) / d 运算结果为： 50