The topic of regular expression

Ask, the answer is?

Why is the answer?

CodePudding user response:

The answer is in my heart com

It's a pity that no option

CodePudding user response:

ifcode.com

CodePudding user response:

Complete matching 0-14 www.ifcode.com
Group 1. 0 to 14 www.ifcode.com
Group 2. 0 to 3 WWW
Group 3. 4-14 ifcode.com
Group 4. 4-10 ifcode
Group 5. 11-14 com
Options: A

CodePudding user response:

Short answer: choose A=ifcode.com

A:

 
((WWW). ((ifcode.) (com))) 
_______ | | the... 0 0, the default is matching the whole, complete, all of the string 
Count from left to right is which a left parenthesis: 
1 _______ | | the... the first bracket is group (1) 
Three _____ | | _2_ | |... the second bracket and the scope of the third parentheses, respectively, as shown in the left 
| ___4__ | | _5_ | the scope of the fourth and fifth brackets brackets, respectively, as shown in the left 

- & gt; So here's group (3) corresponds to: 
((ifcode.) (com)) 
Parts, namely: 
Ifcode.com 

Also can use tools to see more clearly:

RegExr: Learn, Build, & amp; Test the RegEx



Comments:
Ask so out, is to want to test you:
(1) know the default group (0), always said is all the result of the match, or know the existence of the group (0)
(2) to investigate group calculation rules, you are right number from left to right, the minimum is 1, each left parenthesis (it corresponds to the serial number of the group

Depth evaluation:

In fact, the above this kind of writing, it is not good to write
Should use the name group to write, logic clearer

The complete code is as follows:

 

The import re 

InputDomainStr="www.crifan.com" 
(domainP="? P (? P WWW). (? P (? P Crifan). (? P Com))) 
"FoundDomain=re search (domainP inputDomainStr) 
If foundDomain: 
WholeMatchStr=foundDomain. Group (0) 
Print (" wholeMatchStr=% s "% wholeMatchStr) 

WholeDomain=foundDomain. Group (" wholeDomain ") 
Print (" wholeDomain=% s "% wholeDomain) 
SubDomain=foundDomain. Group (" subDomain ") 
Print (" subDomain=% s "% subDomain) 
HostOrg=foundDomain. Group (" hostOrg ") 
Print (" hostOrg=% s "% hostOrg) 
The host=foundDomain. Group (" host ") 
Print (" host=% s "% host) 
Org=foundDomain. Group (" org ") 
Print (" org=% s "% org) 

# wholeMatchStr=www.crifan.com 
# wholeDomain=www.crifan.com 
# subDomain=WWW 
# hostOrg=crifan.com 
# host=crifan 
# org=com 

Print ("="* 80) 

Further optimization:

(1)
The above points, is able to match any character, and not just point itself, but here is meant only matching point itself, so should be optimized for \.

(2) match more domain name
If you want to match to other more domains, such as:

Book.crifan.com
www.crifan.org

Wait for a circumstance, you can use the following code:

 

InputDomainList=[
"Www.crifan.com", 
"Book.crifan.com", 
"Wiki.crifan.com", 
"Www.crifan.net", 
"Www.crifan.org", 
] 

For curIdx eachDomainStr enumerate in (InputDomainList) : 
Print (" % s % s % s "% (" -" * 20, curIdx, "-" * 20)) 
Print (" eachDomainStr=% s "% eachDomainStr) 
(multiDomainP="? P (? P The \ w +). (? P (? P The \ w +). (? P The \ w +))) 
"FoundMultiDomain=re search (multiDomainP eachDomainStr) 
If foundMultiDomain: 
CurWholeMatchStr=foundMultiDomain. Group (0) 
Print (" curWholeMatchStr=% s "% curWholeMatchStr) 

CurWholeDomain=foundMultiDomain. Group (" wholeDomain ") 
Print (" curWholeDomain=% s "% curWholeDomain) 
CurSubDomain=foundMultiDomain. Group (" subDomain ") 
Print (" curSubDomain=% s "% curSubDomain) 
CurHostOrg=foundMultiDomain. Group (" hostOrg ") 
Print (" curHostOrg=% s "% curHostOrg) 
CurHost=foundMultiDomain. Group (" host ") 
Print (" curHost=% s "% curHost) 
CurOrg=foundMultiDomain. Group (" org ") 
Print (" curOrg=% s "% curOrg) 

# -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
# eachDomainStr=www.crifan.com 
# curWholeMatchStr=www.crifan.com 
# curWholeDomain=www.crifan.com 
# curSubDomain=WWW 
# curHostOrg=crifan.com 
# curHost=crifan 
# curOrg=com 
# -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
# eachDomainStr=book.crifan.com 
# curWholeMatchStr=book.crifan.com 
# curWholeDomain=book.crifan.com 
# curSubDomain=the book 
# curHostOrg=crifan.com 
# curHost=crifan 
# curOrg=com 
# -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
# eachDomainStr=wiki.crifan.com 
# curWholeMatchStr=wiki.crifan.com 
# curWholeDomain=wiki.crifan.com 
# curSubDomain=wiki 
# curHostOrg=crifan.com 
# curHost=crifan 
# curOrg=com 
# -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
# eachDomainStr=www.crifan.net 
# curWholeMatchStr=www.crifan.net 
# curWholeDomain=www.crifan.net 
# curSubDomain=WWW 
# curHostOrg=crifan.net 
# curHost=crifan 
# curOrg=net 
# -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
# eachDomainStr=www.crifan.org 
# curWholeMatchStr=www.crifan.org 
# curWholeDomain=www.crifan.org 
# curSubDomain=WWW 
# curHostOrg=crifan.org 
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