Re: pattern matching: why does the following code evaluate true? (and how do i fix it?)

so it should be:

($key =~ m/.$key2/)
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i was just about to follow up with

($key =~ m/^$key2$/)
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as being how i solved this problem ...

(well how O'Reilly solved it)

i geuss this means that the '.' in the string is interpreted as a wildcard matching to the end of the line?

that's interesting ... please correct me if i'm wrong but if that's the way it works that's a really cool thing to have learned

:)!

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RE: Re: pattern matching: why does the following code evaluate true? (and how do i fix it?) by reptile (Monk) on May 31, 2000 at 03:17 UTC
The '.' matches a single character, any character, except \n (unless using the 's' modifier, to treat the expression as a single line). There are two ways to solve the problem, one is how you did it, and another is to use `/\Q$key2/` as others have said, so the '.' is treated as a literal '.' (along with every other metacharacter). `$key =~ m/^$key2$/; # works $key =~ m/\Q$key2/; # also works` [download] Personally I think the second option is better here. The '.' normally matches the literal '.' and anything else as well, but if your $key contained something like `"INITIAL!LASTNAME"` it would match if `"INITIAL.LASTNAME"` where the pattern. Quoting metacharacters with `\Q$pattern\E` is, at least, more correct, even if the first will work ok with the given input. It'll help you avoid bugs to use the second option. `72656B636148206C72655020726568746F6E41207473754A`	[reply] [d/l]

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RE: Re: pattern matching: why does the following code evaluate true? (and how do i fix it?)
by reptile (Monk) on May 31, 2000 at 03:17 UTC

The '.' matches a single character, any character, except \n (unless using the 's' modifier, to treat the expression as a single line). There are two ways to solve the problem, one is how you did it, and another is to use /\Q$key2/ as others have said, so the '.' is treated as a literal '.' (along with every other metacharacter).

$key =~ m/^$key2$/;   # works
$key =~ m/\Q$key2/;   # also works
[download]

Personally I think the second option is better here. The '.' normally matches the literal '.' and anything else as well, but if your $key contained something like "INITIAL!LASTNAME" it would match if "INITIAL.LASTNAME" where the pattern. Quoting metacharacters with \Q$pattern\E is, at least, more correct, even if the first will work ok with the given input. It'll help you avoid bugs to use the second option.

72656B636148206C72655020726568746F6E41207473754A

[reply]
[d/l]