int2roman.hh
#ifndef INT2ROMAN_HH
#define INT2ROMAN_HH
#include <string>
std::string int2roman( size_t decimal, size_t length = 30 )
{
assert( decimal > 0 && decimal < 1000 );
const size_t nrows = 4;
const size_t ncols = 4;
static size_t table_arabs[ nrows ][ ncols ] = { { 1000, 1000, 1000, 1000 },
{ 900, 500, 400, 100 },
{ 90, 50, 40, 10 },
{ 9, 5, 4, 1 } };
static const char *table_romans[ nrows ][ ncols ] = { { "M", "M", "M", "M" },
{ "CM", "D", "CD", "C" },
{ "XC", "L", "XL", "X" },
{ "IX", "V", "IV", "I" } };
size_t power; // power of ten
size_t index; // Indexes thru values to subtract
std::string roman = "";
roman.reserve(length);
for ( power = 0; power < nrows; power++ )
for ( index = 0; index < ncols; index++ )
while ( decimal >= table_arabs[ power ][ index ] )
{
roman += table_romans[ power ][ index ];
decimal -= table_arabs[ power ][ index ];
}
return roman;
}
#endif