regex with multiple matches, missing first match?

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I have the following code:

my $line = 1 |  0.116 0.088 0.173 0.624;
@prob = $line =~ m/(\b0\.[0-9][0-9][0-9])/g;
print $prob[0], "\n";
print $prob[1], "\n";
print $prob[2], "\n";
[download]

The output of this code is:

0.088
0.0173
0.624
[download]

($prob[3] is undefined) Why is 0.116 not being found?

Fixed square brackets - dvergin 2003-04-21

Comment on regex with multiple matches, missing first match? Select or Download Code

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Re: regex with multiple matches, missing first match? by robartes (Priest) on Apr 22, 2003 at 06:34 UTC
Hmm, your code works for me. I quoted the assignment to $line: `my $line="1 \| 0.116 0.088 0.173 0.624";` [download] The regexp matches as expected in this case. Are you certain that this is the version of the code that produces the problem? CU Robartes-	[reply] [d/l]
Re: regex with multiple matches, missing first match? by nite_man (Deacon) on Apr 22, 2003 at 06:34 UTC
I think problem is in the: `my $line = 1 \| 0.116 0.088 0.173 0.624;` [download] I don't understand what do you mean? Followning code works correctly: `my $line = "0.116 0.088 0.173 0.624"; my @prob = $line =~ m/(\b0\.[0-9][0-9][0-9])/g; print $prob[0], "\n"; print $prob[1], "\n"; print $prob[2], "\n"; print $prob[3], "\n";` [download] -------------------------------- SV* sv_bless(SV* sv, HV* stash);	[reply] [d/l] [select]
Re: regex with multiple matches, missing first match? by agentv (Friar) on Apr 22, 2003 at 12:35 UTC
...this is just a guess, but I believe that whether you quote the assignment string or not makes all the difference in the world. (Although in my tests, the interpreter choked unless I supplied quotes.) But presuming that quotes are not necessary in some contexts, here is what could happen. The OR operator, "\|" has a higher precedence than the assignment, so the fragment "1 \| 0.116" yields "1". That would account for the anomaly that you describe. On the other hand again, I could not get your assignment instruction to run under 5.6 using the debugger interactively. So I have to reiterate the wonder about there being any output at all from your program. ...All the world looks like -well- all the world, when your hammer is Perl. ---v	[reply]