match leading '*' in r.e... how?

[Leor Zolman]

I'm probably going to feel really stupid when I see the answer, but I'm now
stuck nevertheless... I need to match a leading literal '*', and Perl isn't
getting the idea. Reading from standard input, typing "const" into the program
below yields "just const" as expected, but typing "*const" ALSO results in it
just saying "just const", rather than "*const".

This is a simplification of a much more complex r.e. where I need to detect an
asterisk immediately preceding "const", and it isn't working either.

How am I being brain-dead?
-leor

while (<>)
{
if (/const/)
{
print "just const\n\n";
}
elsif (/\*const/)
{
print "*const\n\n ";
}
else
{
print "None.\n";
}
}

[John Bokma]

Re: match leading '*' in r.e... how?

Leor Zolman wrote:
[color=blue]
> I'm probably going to feel really stupid when I see the answer, but I'm now
> stuck nevertheless... I need to match a leading literal '*', and Perl isn't
> getting the idea. Reading from standard input, typing "const" into the program
> below yields "just const" as expected, but typing "*const" ALSO results in it
> just saying "just const", rather than "*const".
>
> This is a simplification of a much more complex r.e. where I need to detect an
> asterisk immediately preceding "const", and it isn't working either.
>
> How am I being brain-dead?
> -leor
>
> while (<>)
> {
> if (/const/)
> {
> print "just const\n\n";[/color]

Nope, /const/ matches *const, constant, fooconstbar etc.

Always print the thingy when debugging... Not a silly message which
assumes your program works (which it doesn't).
[color=blue]
> }
> elsif (/\*const/)
> {
> print "*const\n\n ";
> }
> else
> {
> print "None.\n";
> }
> }[/color]

To fix it: match the most specific one first. Also read how one can
create a "switch" in perl. It will quite likely make your code more
readable.


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