Python learning process (7) string

This section describes how to create and manipulate strings.

(1) Create a string:

You can create strings with either single quotation marks or double quotes:

[Email protected]:/home/sunjimeng/Desktop#Cat text.py#both single and double quotation marks can create a stringstr1='Menangel'str2="Sunjimeng"Print(STR1,' is', STR2) [Email protected]:/home/sunjimeng/Desktop#python3.5 text.pyMenangel isSunjimeng[email protected]:/home/sunjimeng/Desktop#

(2) The value specified in the Access string:

Python does not support single character types, and one character is also used as a string in Python.

Python accesses substrings, you can use square brackets to intercept strings:

[Email protected]:/home/sunjimeng/Desktop#Cat text.py#both single and double quotation marks can create a stringstr1='Menangel'str2="Sunjimeng"Print(STR1,' is', str2)Print('str1[0]=', str1[0])Print('Str2[5:9]', Str2[5:9]) [email protected]:/home/sunjimeng/Desktop#python3.5 text.pyMenangel isSunjimengstr1[0]=mstr2[5:9] Meng

(3) Update the value of the string:

[Email protected]:/home/sunjimeng/Desktop#Cat text.py#both single and double quotation marks can create a stringstr1='Menangel'str2="Sunjimeng"Temp='Hello'+str1;Print('the current string is', temp) temp=temp[:6]+str2Print('the current character Fu Cha is', temp) [Email protected]:/home/sunjimeng/Desktop#python3.5 text.pythe current string is Hello Menangel the current word Fu Cha for Hello Sunjimeng

(4) Escape character:

Similar to the C language, Python uses a backslash (\) to escape characters when special characters are needed in characters.

[Email protected]:/home/sunjimeng/Desktop#Cat text.py#1. Continuation testPrint('Menangel is studying Python language!')#2. Test the back slashPrint('path to Windows system files: C:\\document\\menangel')#3. Test output single and double quotation marksPrint('single quotation mark: \ '; double quotation mark: \ "')#4. Test carriage return and line breakPrint('Test line-break \ n')#Leave a linePrint('Test return \ r')#the carriage return has no obvious effect, what is the use? [Email protected]:/home/sunjimeng/Desktop#python3.5 text.pyMenangel isstudying Python language!windows System file path: C:\Document\MenAngel single quote:'; double quotes: "Test line break Test return

(5) string operator:

String operators operate strings in a non-functional way, which is convenient and fast:

Examples of string operators:

[Email protected]:/home/sunjimeng/Desktop#Cat text.pystr1='Menangel'str2='Sunjimeng'#testing of the 1.+ operatorPrint(str1+' '+str2)#testing of the 2.* operatorPrint((str1+' '))#test for 3.[] and [:] OperatorsPrint(str1[0:2],str1[3])#tests for 4.in and not inPrint('M' inchstr1)Print('M'  not inchstr1)#test of 5.R/RPrint('using the escape character specifier'R'\ "I was surrounded."','Become a','\ "I was surrounded."') [email protected]:/home/sunjimeng/Desktop#python3.5 text.pyMenangel Sunjimengmenangel Menangel menangel Me atruefalse after using the escape character \"I was surrounded by the ' become"I was surrounded."

(6) format string%:

Python supports the output of formatted strings. Although this may use a very complex expression, the most basic usage is to insert a value into a string that has the string format of%s.

In Python, string formatting uses the same syntax as the sprintf function in C.

Python string formatting symbols:

format string Output instance:

[Email protected]:/home/sunjimeng/Desktop#Cat text.pyName='Menangel'Sex='male' Age=19Print('My personal information is: name=%s,sex=%c,age=%d'%(name,sex,age)) #方法1Print("My personal information is: name=% (name) s,sex=% (Sex) c,age=% (age) D"%{'name':'Menangel','Sex':'male',' Age': 19}) #方法2 [email protected]:/home/sunjimeng/Desktop#python3.5 text.pyMy personal information is: name=menangel,sex= male, age=19My personal information is: name=menangel,sex= Male, age=19

Formatting operator Auxiliary directives:

(7) Three quotation marks (triple quotes):

Three quotes in Python can copy complex strings: Python three quotes allow a string to span multiple lines, and the string can contain line breaks, tabs, and other special characters.

The syntax for a triple quotation mark is a pair of consecutive single or double quotes (usually paired).

>>> tempstr=" ' hello ... Menangel"print(tempstr) Hello Menangel>>> tempstr'  Hello, \nmenangel'

Three quotation marks Let the programmer out of the mire of quotation marks and special strings, and keep a small piece of string in the form of a so-called WYSIWYG (what is WYSIWYG) format.

A typical use case is that when you need a piece of HTML or SQL, a special string escape is cumbersome when you use a string combination.

" " cursor.execute (  'CREATE TABLE users (  login VARCHAR (8), UID Integer,prid INTEGER)')

(8) Unicode string:

It is simple to define a Unicode string:

>>> temp=u' hello menangel'print(temp) Hello Menangel>>> U'hello\u0020world! The '   #被替换的 \u0020 identity indicates that a Unicode character (a blank space) with encoded value 0x0020 is inserted at the given location.  'Hello world! '

The lowercase "u" before the quotation mark indicates that a Unicode string is created here. If you want to add a special character, you can use Python's Unicode-escape encoding.

Python learning process (7) string