I am trying to write a Regex validator (Python 3.8) to accept strings like these:
foo
foo,bar
foo, bar
foo , bar
foo , bar
foo, bar,foobar
This is what I have so far (but it matches only the first two cases):
^[a-zA-Z][0-9a-zA-Z] (,[a-zA-Z][0-9a-zA-Z] )*$|^[a-zA-Z][0-9a-zA-Z]
However, when I add the whitespace match \w, it stops matching altogether:
^[a-zA-Z][0-9a-zA-Z] (\w ,\w [a-zA-Z][0-9a-zA-Z] )*$|^[a-zA-Z][0-9a-zA-Z]
What is the pattern to use (with explanation as to why my second pattern above is not matching).
CodePudding user response：
\w matches [0-9a-zA-Z_] and it doesn't include whitespaces.
What you need is this regex:
^[a-zA-Z][0-9a-zA-Z]*(?:\s*,\s*[a-zA-Z][0-9a-zA-Z]*)*$
RegEx Details:
^: Start[a-zA-Z][0-9a-zA-Z]*: Match a text starting with a letter followed by 0 or more alphanumeric characters(?:: Start non-capture group\s*,\s*: Match a comma optionally surrounded with 0 or more whitespaces on both sides[a-zA-Z][0-9a-zA-Z]*: Match a text starting with a letter followed by 0 or more alphanumeric characters
)*: End non-capture group. Repeat this group 0 or more times$: End