Using a regex search pattern

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

Hi,

I am writing a script to search through a ASCII file for a pattern <BOXIND NUM="x" ID="BX1.xx.xxx"/> and push the contents of the ID to a array.

while ($file =~ /<BOXIND NUM=\"(.+)\" ID=\"(.*?)\"\/>/g) {push(@ind,$2);}

@ind is the array to which I need to add the ID values. I there are two BOXIND elements in a same line, this regex returns only the last found element in that line. Can someone let me know what went wrong in this pattern?

Sriram

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Re: Using a regex search pattern by Corion (Patriarch) on Jun 21, 2006 at 09:34 UTC
In your regex, `/<BOXIND NUM=\"(.+)\" ID=\"(.*?)\"\/>/g`, the `.+` part is greedy and gobbles up too much. You want `.+?`, or better, `[^"]+` in there to stop the regex from matching outside of the attribute field. Maybe you want to look at XPath and/or an HTML parser instead, at least if your task is anything beyond simple extraction ;)	[reply] [d/l] [select]
Re: Using a regex search pattern by jwkrahn (Abbot) on Jun 21, 2006 at 10:11 UTC
You probably want something like this: `push @ind, $file =~ /<BOXIND NUM=".+?" ID="(.*?)"\/>/g;` [download]	[reply] [d/l]
Re: Using a regex search pattern by leocharre (Priest) on Jun 21, 2006 at 13:57 UTC
`while ( $file =~/<BOXIND\s+NUM\s=\s"(\d+)"\s+ID\s=\s"([\w\.]+)"\s* +\/>/ig) { push(@ind,$2); }` [download] The dot+ matches as much as possible. \s+ means there must be at least one whitespace char (tab, space, carriage return). \s* means there might be whitespace. the part [\w\.]+ means match at least one character comprising of any "word character" (a-z caps and lower, 0-9 and _) and the dot. If the ID contained a parenthesis, an ampersand, the match would fail. Look into lookahead and lookbehind too.. ( and .* means "how hard can i make life for myself") :)	[reply] [d/l]