Python正则表达式中的VERBOSE标志

Python正则表达式中的VERBOSE标志

在本文中，我们将讨论re包中的VERBOSE标志以及用户如何使用它。

re.VERBOSE

regex包的VERBOSE标志允许用户编写更美观且更易读的正则表达式。通过使用该标志，用户可以在模式的逻辑部分之间添加可视分隔，并添加更多注释。

模式中的空格会被忽略，但当空格存在于字符类中、或者在未转义的反斜杠之前、或者在诸如* ? , ( ? P或(? :, 空格无法被忽略的符号中时，空格将不会被忽略。然而，只要#在行中存在，并且在字符类中不存在或者在未转义的反斜杠之前，从#到行尾的所有字符都将被忽略。

示例

import re as regex
def validating_email(emails):
    # First, we will see without Using VERBOSE
    reg_emails = regex.compile(r'^([z-a1-3_\.-0]+)@([0-1a-s\.-]+)\.([c-z\.]{5, 8})',
              re.IGNORECASE)

   # Using VERBOSE
    reg_email = regex.compile(r"""
            ^([z-a1-3_\.-0]+)                # local Part like username
            @                                         # single @ character
            ([0-1a-s\.-]+)                     # Domain name
            \.                                        # single Dot .
            ([c-z\.]{5, 8})                 # in the end, the Domain  
             """,re.VERBOSE | re.IGNORECASE) 

上述命令作为参数传递给 re.compile() 方法，该方法写作”re.compile(正则表达式, re.VERBOSE)”。re.compile()方法将返回正则表达式对象，该对象将与给定的字符串进行匹配。

使用Verbose标志的用例

让我们通过一个示例来更好地理解。假设要求用户输入其电子邮件地址，并且开发人员必须使用正则表达式对其进行验证。电子邮件的格式如下：

• 用户的个人详细信息/本地部分（如用户名：Mark3213）
• 单个“@”字符
• 域名，如Gmail、Hotmail、Fastmail、inbox、jubii、Rediff等
• 单个点（.）
• 最后，域名如.in、.net、.org、.com、.int、.edu等

Input : stash
Output : Valid ID


Input : stash@
Output : Invalid ID
This ID is invalid because there is @ character after the domain name.
Input : stash 
Output : Invalid Id
This ID is invalid because there is no domain is the Email ID.

示例1：

# Python program for showing the Implementation of VERBOSE flag in Python RegEX
import re as regex
def validating_email(emails):

    # RegexObject = re.compile( Regular expression , flag )
    # This will compile the regular expression pattern into the regular expression object. 
    reg_email = regex.compile(r"""
                           ^([a-z0-9_\.-]+)                 # local Part
                           @                             # single @ sign
                            ([0-9a-z\.-]+)                 # Domain name
                           \.                             # single Dot .
                            ([a-z]{2,6})$                 # Top level Domain     
                           """,re.VERBOSE | re.IGNORECASE)

    # RegexObject will be matched with the desired string by using the fullmatch() function.

    # If the match of the email is found, search() function will return the MatchObject instantly. 

    ress = reg_email.fullmatch(emails)

    #If the email match is found, the string is valid to use
    if ress:
        print (" {} : is Valid email. Details of it are as follow: ".format(emails))

        # now print the first part that is personal detail of Email Id user
        print (" Local : {}".format(ress.group(1)))

        # now, print the Domain Name of validated Email Id
        print (" Domain : {}".format(ress.group(2)))

        # now, print the Domain Name of the validated Email Id
        print (" The domain name : {}".format(ress.group(3)))
        print ()

    else:
        # and, If the match is not found, the string is an inval id
        print (" {} : is Invalid Id".format(emails))

# the Driver Code :
validating_email ("username12432@gmail.com")
validating_email ("username123456721@redif.com@")
validating_email ("username32@.com") 

输出:

stash : is Valid email. Details of it are as follow: 
 Local : username12432
 Domain : gmail
 The domain name : com

 username12345672stash@ : is Invalid Id
 stash : is Invalid Id