RosettaCodeData/Task/Roman-numerals-Decode/Lua/roman-numerals-decode.lua

26 lines
695 B
Lua

function ToNumeral( roman )
local Num = { ["M"] = 1000, ["D"] = 500, ["C"] = 100, ["L"] = 50, ["X"] = 10, ["V"] = 5, ["I"] = 1 }
local numeral = 0
local i = 1
local strlen = string.len(roman)
while i < strlen do
local z1, z2 = Num[ string.sub(roman,i,i) ], Num[ string.sub(roman,i+1,i+1) ]
if z1 < z2 then
numeral = numeral + ( z2 - z1 )
i = i + 2
else
numeral = numeral + z1
i = i + 1
end
end
if i <= strlen then numeral = numeral + Num[ string.sub(roman,i,i) ] end
return numeral
end
print( ToNumeral( "MCMXC" ) )
print( ToNumeral( "MMVIII" ) )
print( ToNumeral( "MDCLXVI" ) )