In one of python, and is commonly say == operators, mainly used to detect whether two variables are equal, returns True or False, specifically the difference between what it?
I. Introduction
In the explanation is the difference between == and explain directly to the built-in function id () , in fact, in the article python variable data types and immutable data types are also built-in function id () had to explain, is mainly used to obtain the memory address of the variable ! Now do not do too much to explain about memory, you can put the memory address of the string of numbers as symbols, like the same memory address each person has a card number!
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# !usr/bin/env python # -*- coding:utf-8 _*- """ @Author: Why grief @Blog (personal blog address): shuopython.com @WeChat Official Account (micro-channel public number): ape says python @Github:www.github.com
@File:python_is.py @Time:2019/10/26:25
@Motto: short step a thousand miles, no small streams converge into a wonderful required the ocean, the program of life relentlessly accumulate! """
a = 5 b = False c = "hello"
Print ( "A memory address: {}" . the format ( ID ( A ) ) ) Print ( "B Memory Address: {}" . the format ( ID ( B ) ) ) Print ( "memory address C: {}" . the format ( ID ( C ) ) ) |
Output:
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a memory address: 1,784,504,608 b Memory Address: 1784012992 c memory addresses: 2126520897696 |
Two .python operator ==
If the two variables are equal, then the operator == established, returns True; conversely return False ; sample code is as follows:
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a = 3 b = 3 print(a==b)
# Integer and floating point comparison a=3 b = 3.0 print(a==b)
a=3 b = 2.9999 print(a==b)
# 字符串比较 a = "hello world" b = "HELLO WORLD" c = "hello " d = "hello world" print(a==b,a==c,b==c,a==d) |
输出结果：
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True True False False False False True |
三.python运算符 is
1.两个变量的值相等；
2.变量地址也相同(可以通过内置函数id获取变量内存地址)；
如果同时满足以上两个条件，运算符 is 才成立，返回True；反之，不满足其中任何一个条件都会返回False；示例代码如下：
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a = 333333 b = 333333.0 print(id(a)) print(id(b))
print(a is b) print("***"*20)
a = 3 b = 3 print(id(a)) print(id(b))
print(a is b) print("***"*20)
a = "hello world" b = "HELLO WORLD" c = "hello " d = "hello world" print(id(a)) print(id(b)) print(id(c)) print(id(d))
print(a is b,a is c,b is c,a is d) |
输出结果：
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2039213240016 2039234381168 False ************************************************************ 1784504544 1784504544 True ************************************************************ 2039217328240 2039217328176 2039217247376 2039217328240 False False False True |
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