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ceremonial Python Column No 21 piece , Classmate, stop , Don't miss this from 0 The beginning of the article ！

Today, let's talk about string types , I have written two articles in total 1.5 The foundation of ten thousand words is repeated , It involves a lot of basic knowledge , But the string still needs to be talked about more .

The first two are in the same column of this article , Welcome to your attention . Let's start with .

Take a look back. ： String and long string

Python It's simple , There is no special one char（Character） type （ Have done C/Java My classmates are familiar with it ）

stay Python in , By single quotes / Double quotes / The three quotation marks are all strings ！

Let's see what the string looks like

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2021/10/30 10:13  In the morning 
# @Author : LeiXueWei
# @CSDN/Juejin/Wechat:  Lei Xuewei 
# @XueWeiTag: CodingDemo
# @File : string_demo.py
# @Project : hello


text1 = " Continuous learning and continuous development , I'm Lei Xuewei "
text2 = ' Continuous learning and continuous development , I'm Lei Xuewei '
assert text1 == text2  #  They are python It's the same inside ！

#  Substring of string 

print("1char substring : %s and type %s "%(text1[0], type(text1[0]))) # We see that although it is a character ,python Also treat it as a string , because python There is no string type in ！
print(text1[0:4])
print(text1[4:])
print(text1[:4])

longtext = """
 Continuous learning and continuous development , I am a 【 Lei Xuewei 】！
 Programming is fun , The key is to understand the technology thoroughly .
 Welcome to wechat , Like support collection !
"""
print(longtext)
 Copy code 

Readers can directly copy the running code , The school committee added the operation effect diagram ：

Special characters ： How to output quotation marks in a string / Line break ？

As mentioned earlier, every programming language has reserved keywords （ such as ‘break’,‘continue’,‘for’ wait ）.

Some characters in the string will not be printed directly , In a string processing system , They are special , For example, single quotation marks appear in single quotation mark text . For example, how to save a string and wrap it .

So the concept of escape character appears in many languages . Usually as follows

\ Followed by a character 
 such as ：\n, \\, \'
 Copy code 

Next, the school committee has prepared some codes to show the escape characters , From high frequency to low frequency ：

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2021/10/30 10:13  In the morning 
# @Author : LeiXueWei
# @CSDN/Juejin/Wechat:  Lei Xuewei 
# @XueWeiTag: CodingDemo
# @File : string_demo2.py
# @Project : hello

#  Commonly used escape characters 
print("*" * 16)
print(" The following are the escape symbols used from high frequency to low frequency according to Lei Xuewei ")
print("\'=[']")  #  Escape output single quotation marks , Here we show that in a string with double quotation marks, you don't have to ！ There is no need to escape in a three quote long string 
print("\"=["]")  #  Escape output double quotes , Here we show that in a string with single quotation marks, you don't have to ！ There is no need to escape in a three quote long string 
print("\n=[\n]")  #  Line feed output 
print("\r=[\r]")  #  Move the cursor to the beginning of the line , So this line of output is just ']'
print("\=[\]")  #  Escape output '' Symbol 
print("\t=[\t]")  #  Horizontal tabs , Output Tab Key equivalent effect , commonly 4 A space （ Can be in PyCharm Enter... On a blank line Tab Look, I jumped a few spaces ）
print("\b=[\b]")  #  Move the cursor forward one bit 
# print("\v=[\v]") #  Vertical tabs ,  The school committee chose to ignore , This tab is in Java There is no support in , It belongs to a relatively rare type 
print("*" * 16)
 Copy code 

The operation effect is as follows ：

Of course, there are other escape characters , I don't often and don't want to mention , Ha ha ha

The next article will introduce the operation of writing string .

by the way , like Python Friend, , Please pay attention to Python Basic column or Python From getting started to mastering the big column

Continuous learning and continuous development , I'm Lei Xuewei ！
Programming is fun , The key is to understand the technology thoroughly .
Welcome to wechat , Like support collection !