[Tutor] Symbol re question

[Danny Yoo]

On Tue, 18 Sep 2001, Sean 'Shaleh' Perry wrote:

> 
> On 18-Sep-2001 robert frank brenart wrote:
> > 
> > Alright, this should be easy and it's being a pain... I just want to find
> > out if my string is all numbers.
> > 
> > So I run...
> > if ((re.match("[0-9]+", mystring)) != None):
> >       print "Pass"
> > else:
> >       print "Fail"
> > 
> > But that matches things like 10:45 and 3f, which I don't want it
> > to.  What'm I overlooking?
> > 
> 
> A regex matches any part of a string.  if you want the string to ONLY be
> numbers you need to say so in the regex.  Try this:
> 
> r"^[0-9]+$"
> 
> that says "from the start of my string '^', match a string of numbers
> '[0-9]+' then the end of string '$'".  The 'r' before the string tells
> python to read this as a raw string and should be used before any
> regex string.


Somewhat related: be aware that "match" is somewhat different from
"search" in Python's regular expressions:

    http://www.python.org/doc/lib/matching-searching.html

If we're using the anchors '^' and '$', it might be good to use
re.search().