Comments on: How to parse decimal numbers within a string http://programmingzen.com/2006/02/05/how-to-parse-numbers-in-a-string/ By Antonio Cangiano, Software Engineer & Technical Evangelist at IBM Sat, 31 Jul 2010 03:23:54 +0000 hourly 1 http://wordpress.org/?v=3.0 By: Tore Darell http://programmingzen.com/2006/02/05/how-to-parse-numbers-in-a-string/#comment-61 Tore Darell Tue, 30 Nov 1999 00:00:00 +0000 http://72.52.169.158/~antonioc/2006/02/05/how-to-parse-numbers-in-a-string/#comment-61 Nice. I found I had to make the matching group in the second regex non-capturing, though, as the String#scan method would only return arrays of group matches if they're present (containing nil if it wasn't scientific notation), but this worked on both "classic" numbers and numbers written with scientific notation: <pre><code> numbers = s.scan /[-+]?\d*\.?\d+(?:[eE][-+]?\d+)?/ </code></pre> And, to easily turn the Strings returned by String#scan in to Integers and Floats, just do <pre><code> numbers.map{|n| n.include?('.') ? n.to_f : n.to_i} </code></pre> Nice. I found I had to make the matching group in the second regex non-capturing, though, as the String#scan method would only return arrays of group matches if they’re present (containing nil if it wasn’t scientific notation), but this worked on both “classic” numbers and numbers written with scientific notation:


    numbers = s.scan /[-+]?\d*\.?\d+(?:[eE][-+]?\d+)?/

And, to easily turn the Strings returned by String#scan in to Integers and Floats, just do


    numbers.map{|n| n.include?('.') ? n.to_f : n.to_i}
]]> By: federico http://programmingzen.com/2006/02/05/how-to-parse-numbers-in-a-string/#comment-62 federico Tue, 30 Nov 1999 00:00:00 +0000 http://72.52.169.158/~antonioc/2006/02/05/how-to-parse-numbers-in-a-string/#comment-62 Isn't more correct something like: /[+-]?\d+(\.\d+)?/ Since your regexp will match something like .5 without any digit before the decimal point... or it's that what you want? :) Isn’t more correct something like:

/[+-]?\d+(\.\d+)?/

Since your regexp will match something like .5 without any digit before the decimal point… or it’s that what you want? :)

]]> By: Antonio Cangiano http://programmingzen.com/2006/02/05/how-to-parse-numbers-in-a-string/#comment-63 Antonio Cangiano Tue, 30 Nov 1999 00:00:00 +0000 http://72.52.169.158/~antonioc/2006/02/05/how-to-parse-numbers-in-a-string/#comment-63 Hi Federico, .5 is consider 0.5 in several countries. It is intentional. ;-) Hi Federico,
.5 is consider 0.5 in several countries. It is intentional. ;-)

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