Matching two real numbers in a string using regex

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

Good morning, I'm trying to match 2 (+ -)real numbers separated by "to" and then extract and print a range for those numbers. This regex does not extract the second real number properly. Can u help?

#!/usr/bin/perl

while (<>) {
        print if m!(-?\d*?.?\d+)to(-?\d*?.?\d+)!m;
        print "$1\n$2\n";
        print "$_\n" for ($1 .. $2);
        }


giving the result:

[barry@localhost]$ ./g
4.5to6.8
4.5to6.8
4.5
6
4
5
6

the "4.5" extracts properly but not the "6.8",
it gets truncated to "6"....?
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Re: Matching two real numbers in a string using regex by japhy (Canon) on Sep 06, 2002 at 03:13 UTC
Remove the '?' from the '\d'. It's making it try to match as few digits as possible. `/(-?\d\.?\d+)to(-?\d\.\d+)/` will work. _____________________________________________________ Jeff`[japhy]`Pinyan: Perl, regex, and perl* hacker, who'd like a job (NYC-area) `s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;`	[reply] [d/l]
Re: Matching two real numbers in a string using regex by Silicon Cactus (Scribe) on Sep 06, 2002 at 14:35 UTC
Why use a regex for this at all, when a simple split will do? `my($FirstNo, $SecondNo) = split /to/;` Much more simple, IMHO.	[reply] [d/l]
Re^2: Matching two real numbers in a string using regex by Flexx (Pilgrim) on Sep 06, 2002 at 14:45 UTC
Since this would allow `wantoeat?` to be input? Anyway, for a quick shot you certainly got a point.. ;)	[reply] [d/l]
Re: Re^2: Matching two real numbers in a string using regex by Silicon Cactus (Scribe) on Sep 06, 2002 at 18:54 UTC
Right. But without sample input, who's to know if that is likely? <grin>	[reply]
Re^4: Matching two real numbers in a string using regex by Flexx (Pilgrim) on Sep 07, 2002 at 12:38 UTC
Re: Matching two real numbers in a string using regex by Flexx (Pilgrim) on Sep 06, 2002 at 14:42 UTC
Hi! just for fun, I played around with this a little. `#!/usr/bin/perl while (<>) { print if m/^([+-]?\d\.\d)\s+([+-]?\d.\d)$/; print "$1 ~ ", int $1, "\n$2 ~ ", int $2, "\n"; print "$_\n" for (int $1 .. int $2); }` [download] Putting the regex between `^$` makes input like `.1 2foo` illegal (and would have fixed your regexp, too, BTW). `[+-]?` allows to have a positive, negative or no sign. So this now takes all of 1 .1 1. 1.1 . all prefixed with + or - or nothing. Note that . is fine -- int converts it to 0. `int $1 .. int $2` make it work with input like `0.3 4` (where your snipplet was broken). The `\s+` (one or more whitespace was just because I was annoyed by having to type "to" all the time during playing around. ;) Hope you find all that interesting.. ;) So long, Flexx	[reply] [d/l] [select]