Collation of real questions in Python interview

Hee hee hee hee hee 2020-11-13 01:54:04
collation real questions python interview

python The interview real question arrangement


python in is and == The difference between

stay python in , An object has three elements ,value,id and type.
“==” The main judgment is that of two objects value Are they the same? ,
“is” Also called identity operator , Will judge both ID Are they the same? .

sketch read、readline and readlines The difference between

read: Read and output all the contents of the file ;
readline: A line that reads the contents of the file ;
readlines: Read all the contents of the file , Return a list by row .

Give examples of at least two ways to create a dictionary
  1. Direct adoption dict={key:value} establish
  2. Built in method fromkeys.dict = {}.fromkeys((key1,key2),value), The dictionary created in this way is suitable for key Have the same value value , The default is None.
  3. zip Indirect creation userinfo = zip.([“username”,“Id”],[“lalala”,“123”]),dict(userinfo), You can create a dictionary .
*args,**kwargs The role of ? How to use ?

When the parameters of a function are uncertain , have access to args and kwargs,args No, key value ,kwargs Yes key value .
When we don't know how many arguments to pass to the function , For example, we pass a list or tuple to , We just use *args
When we don't know how many keyword parameters to pass , Use **kwargs To collect keyword parameters

python in match() and search() The difference between ?

match() The function only detects the beginning position of the string and the detected string match , If the match is successful, the result will be returned , Otherwise return to None;
search() The function looks for a pattern match throughout the string , Only to find the first match and then return an object with matching information , This object can be called by group() Method to get the matching string , If the string doesn't match , Then return to None.


Explain it. python The ternary expression in

if_suite if expression1 else else_suite

expression1 : Judge the condition
if_suite:True Value
else_suite:False Value

Python How to realize multithreading in ?

establish Thread Example , Pass it a function
establish Thread Example , Pass it a callable instance of the class
The derived Thread Subclasses of , And create instances of subclasses
Use thread pool

Interpretative inheritance

Inheritance describes the relationship between things , When we define a class When , From an existing class Inherit , Properties of the parent class 、 Method , Will be inherited to subclass .

What is? Flask?

Flask yes Python Write a lightweight Web Application framework . Its WSGI The tool box uses Werkzeug , The template engine uses Jinja2.Flask Use BSD to grant authorization . Two of the environmental dependencies are Werkzeug and jinja2, This means it doesn't have to rely on external libraries . Because of this , We call it a lightweight framework .

How to be in Python Manage memory in ?

Python The reference counting mechanism is used to manage the allocated memory .Python Each object of has a reference count , This reference count shows how many objects are pointing to it . When the reference count is 0 when , Free the memory of the object . To solve the problem of circular reference ,Python Provides “ Mark - eliminate ” Law , Objects used to release circular references .


python2 and python3 Of range(100) The difference between .

stay python2 in ,range(100) It returns a list ,
stay python3 in ,range(100) It returns an iteratable object .

In a word, explain what kind of language can be used with decorators .

Functions can be passed as arguments in languages where decorators can be used

python What are the built-in data types ?

python Built in data types have reshaping (int)、 floating-point (float)、 The plural (complex)、 Boolean (bool)、 character string (str)、 list (list)、 Tuples (tuple)、 aggregate (set)、 Dictionaries (dict)、

In this paper, a brief introduction of object-oriented is given __new__ and __init__ The difference between ?

__new__ It's an action that takes place before an object is created , The accepted parameters are cls, Responsible for the creation of objects ;
__init__ It's the action after the object is created , Perfect the properties of objects , The accepted parameters are self.
Objects are generated in new Done in .

sketch with Method to open the processing file to help us do ?

with Method to open a file , We can complete the operation of the file , Close files automatically , Ensure the security of the file .


Big data file reading

① Using generators generator;

② Iterator iterates :for line in file

The difference between an iterator and a generator

Iteratable object : Can act directly on for The object of the cycle ;
An iterator is an object used for iterative operations , Iterators are iteratable objects . Simply speaking , An iterator can be next() Function calls and continuously returns the next value ;
The nature of a generator is also an iterator , The difference between iterators and iterators is that yield, The generator needs to use yield.

The function and function of decorators

The essence of decorator is a function , It's just that the decorator's parameters don't look like normal functions , The argument to the decorator is a function , Its function is that it allows other functions to add additional functions without modifying the code , The return value of the decorator is also a function object . In development , We need to be open and closed , For functions already implemented , We will not modify it , At this point, we need decorators to extend it .

Let's talk about it briefly GIL

GIL(Global Interperter Lock) Global interpreter lock ,GIL yes Python Explain the level of lock , Solve the problem of multiple threads competing for resources in the interpreter ( Multiple threads compete for system resources , Are waiting for a part of the object to be de occupied , As a result, no one wants to unlock it first , Then wait for each other , The program can't go on ).

How to improve python Operating efficiency
  1. Optimize the cycle
  2. More use pthon Modules that have been packaged in
  3. Use the newer Python edition


What's the difference between a list and a tuple ?

First , Lists and tuples are collections that can store any data type ,
But tuples are immutable .

explain Python Medium help() Functions and dir() function .

help Function is a built-in function , A detailed description of the purpose of a function or module .
dir() Function time python Built in functions for ,dir() When a function has no arguments , Returns the variables in the current range 、 List of types of methods and definitions , With parameters , Return the properties of the parameter 、 Method list

When to exit Python Whether all memory allocation will be released when the ?

The answer is No . Variables with object circular references or global namespace references , stay Python Exit is often not released .

What is monkey patch ?

Dynamic replacement of properties at run time , It's called monkey patch .

Explain it. *args and **kwargs.

see Day1*args,**kwargs The role of ? How to use ?

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