[Tutor] Need help on regular expresions

[Manprit Singh]

Dear Richard,

I know this can be done with string methods, I was just willing to know if
this can be done using re in an easy way or not .

Thanks for your mail.

Regards
Manprit Singh


On Sat, Nov 6, 2021 at 9:00 PM Richard Damon <Richard at damon-family.org>
wrote:

> My first thought is that this sounds very much like a case of having a
> hammer, so you want to treat something as a nail even if it isn't really
> one.
>
> If this is a homework problem about thinking about regular expressions,
> that would be one thing, but if the problem really is identifying if the
> string has the right character membership, regular expressions are not
> the right tool.
>
> Simplest would seem to be to iterate through the string, classify each
> character and keep a count, and then check those counts.
>
> A regular expression can test a string for the presence of at least 3
> digits with a pattern something like (in english):
>
> 0 or more characters, 1 digit, 0 or more characters, 1 digit, 0 or more
> characters, 1 digit, 0 or more characters.
>
> Using patterns like this you can check for each category requirement
> with a separate expression.
>
> Getting a regular expression to check multiple parallel checks at the
> same times gets into much more advanced topics, and I would need to
> double check that python supports that level of syntax, but even if it
> does, unless there is some real reason it needs to be a single regular
> expression, it is much clearer to use multiple expressions for each
> requirement.
>
>
> On 11/6/21 11:01 AM, Manprit Singh wrote:
> > Dear sir ,
> >
> > A little modification in my last mail,
> >
> > Dear Sir ,
> > Let's say i have to find if a string in question is of length 10,
> contains
> > four digits, one underscore and all other 5 characters must be alphabets
> > (upper or lowercase)
> >
> > How would I do it with regular expressions ? Since this problem will be
> > very ugly with regular string methods,  that's why I would like to try it
> > with re's.
> >
> > The below given example only checks if the string x is made up of 10
> > characters and contains numbers from 0-9 an underscore and alphabets a-z
> > and A-Z, but no count checks of numbers and alphabets and underscore .
> How
> > to do it?
> >
> > import re
> > x = "aG4cD1_23fg"
> > if re.fullmatch(r'\w{10}', x):
> >      print("Match found")
> > else:
> >      print("No match")
> >
> > Kindly guide
> >
> > Regards
> > manprit Sing
> >
> > On Sat, Nov 6, 2021 at 8:23 PM Manprit Singh <manpritsinghece at gmail.com>
> > wrote:
> >
> >> Dear Sir ,
> >> Let's say i have to find if a string in question is of length 10,
> contains
> >> at least four digits, one underscore and all other 5 characters must be
> >> alphabets (upper or lowercase)
> >>
> >> How would I do it with regular expressions ? Since this problem will be
> >> very ugly with regular string methods,  that's why I would like to try
> it
> >> with re's.
> >>
> >> The below given example only checks if the string x is made up of 10
> >> characters and contains numbers from 0-9 an underscore and alphabets a-z
> >> and A-Z, but no count checks of numbers and alphabets and underscore .
> How
> >> to do it?
> >>
> >> import re
> >> x = "aG4cD1_23fg"
> >> if re.fullmatch(r'\w{10}', x):
> >>      print("Match found")
> >> else:
> >>      print("No match")
> >>
> >> Kindly guide
> >>
> >> Regards
> >> manprit Singh
> >>
> >>
> >>
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>
> --
> Richard Damon
>
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