Re: Chomp a numerical expression, return the answer.

You want eval. But... you don't want it!

$ perl -lne "print eval"
(7 * 3) + (2 + 1)
24
[download]

Now, to convince you that you don't want it, think about

"system 'rm -rf /'"
[download]

You may be interested in Safe.pm, but that's been reported not to be bullet-proof either.

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Re^2: Chomp a numerical expression, return the answer. by suaveant (Parson) on May 18, 2006 at 16:17 UTC
or at the very least limit the input... Something like `if($exp =~ /^[-+/*%()\s\d]+$/) { print eval $exp; }` [download] or something along those lines it would make it much harder to actually do anything underhanded. Exactly what taint mode encourages people to do. - Ant - Some of my best work - (1 2 3)	[reply] [d/l]
Re^2: Chomp a numerical expression, return the answer. by sub_chick (Hermit) on May 18, 2006 at 17:50 UTC
If `eval` is as big of a No-No as `"system 'rm -rf /' "`, I think I better seek an alternative. I'll do the suggested and put a strict limit on the input via a regex. Es gibt mehr im Leben als Bücher, weißt du. Aber nicht viel mehr. - (Die Smiths)"	[reply] [d/l] [select]