Regular Expression with strings in Python

Question

I am trying to create an expression that will give me an output of yes for strings, 6,7,8 and an output of no for 9 & 10. Any advice would be greatly appreciated!

#The regular expression is ' ^<[^<>]*>$ '
    print ( 'The regular expression used for 5 strings was "^<[^<>]*>$"' )
    string6 = '<an xml tag>'
    string7 =  '<an xml tag>, </closetag>'
    string8 = '<with attribute="77">'
    string9 = '<opentag><closetag>'
    string10 = '</closetag>'

    if re.search( r'^<[^<>]*,>$',string6 ) :
        print( "yes" )
    else:
        print("no")
    if re.search( r'^<[^<>]*,>$',string7 ) :
        print( "yes" )
    else:
        print("no")

    if re.search(r'^<[^<>]*>$',string8):
        print("yes")

    else:
        print("no")

    if re.search(r'^<[^<>]*>$',string9):
        print("yes")

    else:
        print("no")

    if re.search(r'^<[^<>]*>$',string10):
        print("yes")

    else:
        print("no")

This is the result: yes no yes no yes

I am trying to get: yes yes yes no no

Please do *not* parse XML/HTML with regexes: https://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454 — Willem Van Onsem, Oct 02 '18 at 19:30
Try using `beautifulsoup` instead. You'll probably have much better luck! — Swagga Ting, Oct 02 '18 at 19:41
@usr2564301 Yes, it means that the regx has worked if the result is yes. — love2code, Oct 02 '18 at 20:00
So the regex itself can be *anything*? And so @Ruzihm suggestion will work for you? Or (digging deeper) is there a *purpose* beyond each of those regexes, other than "matching"? — Jongware, Oct 02 '18 at 20:31
Are these strings supposed to be examples of a more general rule? Regular expressions are generally used for matching patterns, not specific strings. — Barmar, Oct 02 '18 at 20:50

score 1 · Answer 1 · answered Oct 02 '18 at 20:53

1

If you just have to match those specific strings, just use a regular expression with literal text in an alternation.

regex = r'^(?:<an xml tag>|<an xml tag>, </closetag>|<with attribute="77">)$';
for s in [string6, string7, string8, string9, string10]:
    if (re.search(regex, s)):
        print("yes")
    else:
        print("no")

It's not clear from the question what more general pattern could be used.

answered Oct 02 '18 at 20:53

Barmar

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Unless OP expands the question, we might as well boil it down to `print ("yes yes yes no no")` – Jongware Oct 03 '18 at 21:09

score 1 · Answer 2 · answered Oct 02 '18 at 20:53

The first 3 strings have at least one space character in them and the last 2 don't. If you use a regular expression that's just a single space character, , it will match the first three and not the last two.

string6 = '<an xml tag>'
string7 =  '<an xml tag>, </closetag>'
string8 = '<with attribute="77">'
string9 = '<opentag><closetag>'
string10 = '</closetag>'

if re.search( r' ',string6 ) :
    print( "yes" )
else:
    print("no")
if re.search( r' ',string7 ) :
    print( "yes" )
else:
    print("no")

if re.search(r' ',string8):
    print("yes")

else:
    print("no")

if re.search(r' ',string9):
    print("yes")

else:
    print("no")

if re.search(r' ',string10):
    print("yes")

else:
    print("no")

Regular Expression with strings in Python

2 Answers2