February 1st, 2013, 04:23 PM
Literal period at the beginning of a string?
I'm looking to get the value of a capacitor from the description.
I'm using the following REGEX:
\b(\d|\.)+(PF| PF|UF| UF|NF| NF)
CAP .01UF 10% 25V X5R 0402 I want .01UF, I get 01UF
CAP 0.01UF 10% 25V X5R 0402 I want 0.01UF, I get 0.01UF
So why does it skip the literal period.
I expect that the regex engine does not recognize a literal period as the begining of a word.
Any suggestions would be appreciated.
February 1st, 2013, 04:58 PM
\b means a word boundary and is defined as having a \w on one side and a \W on the other. That's why it finds a boundary between a period (\W) and a number (\w).
For whatever reason the engine decided to match after the period. Probably a result of optimizations - maybe it expanded the beginning of the expression to (\b\d|\b\.) and found the \b\d first. Who knows.
Be more specific with your regex. Try
February 2nd, 2013, 05:40 AM
I do not think it is the result of an optimization. It is just that, in " .", there is no word boundary between the space and the dot.
Try this (Perl syntax):
It will not print anything. But:
my $d = " .";
print $1 if $d =~ /\b(\.)/;
will print "5".
my $d = ".5";
print $1 if $d =~ /\b(\d)/;
The syntax proposed by Requinix should work.
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