Commas in Numbers
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| Revision as of 00:24, 23 November 2006 (edit) Kaiserpanda (Talk | contribs) m ← Previous diff |
Current revision (09:47, 23 November 2006) (edit) (undo) 213.171.204.166 (Talk) (→Solution) |
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| [[Category:CookBook]][[Category:StringRecipes]][[Category:ListRecipes]][[Category:NumberRecipes]] | [[Category:CookBook]][[Category:StringRecipes]][[Category:ListRecipes]][[Category:NumberRecipes]] | ||
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Current revision
[edit] Problem
You need to format a number for printing with commas (or other locale-dependant marks) in the appropriate places. This is important for creating human-legible print copies of reports.
[edit] Solution
Turn the number into a list and then use pattern-matching to insert commas where needed.
partition_integer(N,P) ->
partition_integer(lists:reverse(integer_to_list(N)),P,[]).
partition_integer([A,B,C,D|T],P,Acc) ->
partition_integer([D|T],P,[P,C,B,A|Acc]);
partition_integer(L,_,Acc) ->
lists:reverse(L) ++ Acc.
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Floating-point numbers generally require additional separator, and also an explicit fractional-part length:
partition_float(N,P,FP,L) ->
F = tl(tl(hd(io_lib:format("~.*f",[L,N-trunc(N)])))),
lists:flatten([partition_integer(trunc(N),P),FP,F]).
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Here's an example of the above in action:
1> partition_integer(1918928282, $,). "1,918,928,282" 2> partition_integer(1982928828, $'). "1'982'928'828" 3> partition_float(1982928828.12345, $', $., 6). "1'982'928'828.123450" |
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