A regular expression can tell you two things: Whether there's a match at all, and what some parts in the match are. You are using it in different ways, on two levels:
$row =~ /.*,(.*)/ is a pattern match. It returns whether $row contains the pattern. If you have parentheses in the regex (and you have), then the part of the match within the parentheses is captured - and if you evaluate the pattern match in list context, these captures will be returned as a list. By writing my ($value) you create a list context, therefore you get whatever matched after the last comma.
$row =~ s/,[^,]*$// is a substitution s/text/pattern/. Substitutions change the variable they operate upon, and they return the number of substitutions made, regardless of context. Hence the 1 in the second line: One substitution. You get the substring before the last comma in the variable $row by deleting the last comma and whatever follows it.
If you want the second example to behave like the first, add a capture, and replace the substitution by a match, like this:
my ($val) = ($row =~ /(.*),[^,]*$/);
In reply to Re: difference in regex
by haj
in thread difference in regex
by ovedpo15
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