Fix bug 4112: Translate to roman numerals for numbers higher than 20.

[features.git] / src / Counters.cpp

diff --git a/src/Counters.cpp b/src/Counters.cpp
index 18f523672813a21ea20ec24f327013f8b548b956..fb265764dbd013ba61dda654e744914bb98e8cfd 100644 (file)
--- a/src/Counters.cpp
+++ b/src/Counters.cpp
@@ -6,6 +6,7 @@
  * \author Lars Gullik Bjønnes
  * \author Martin Vermeer
  * \author André Pönitz
+ * \author Richard Heck (roman numerals)
  *
  * Full author contact details are available in file CREDITS.
  */
@@ -243,33 +244,71 @@ char hebrewCounter(int const n)
 }
 
 
-docstring const lowerromanCounter(int const n)
+
+//On the special cases, see http://mathworld.wolfram.com/RomanNumerals.html
+//and for a list of roman numerals up to and including 3999, see 
+//http://www.research.att.com/~njas/sequences/a006968.txt. (Thanks to Joost
+//for this info.)
+docstring const romanCounter(int const n, bool lowercase = false)
 {
-       static char const * const roman[20] = {
-               "i",   "ii",  "iii", "iv", "v",
-               "vi",  "vii", "viii", "ix", "x",
-               "xi",  "xii", "xiii", "xiv", "xv",
-               "xvi", "xvii", "xviii", "xix", "xx"
+       static char const * const ones[9] = {
+               "I",   "II",  "III", "IV", "V",
+               "VI",  "VII", "VIII", "IX"
        };
-
-       if (n < 1 || n > 20)
+       
+       static char const * const tens[9] = {
+               "X", "XX", "XXX", "XL", "L",
+               "LX", "LXX", "LXXX", "XC"
+       };
+       
+       static char const * const hunds[9] = {
+               "C", "CC", "CCC", "CD", "D",
+               "DC", "DCC", "DCCC", "CM"
+       };
+       
+       if (n > 1000 || n < 1) 
                return from_ascii("??");
-       return from_ascii(roman[n - 1]);
+       
+       int val = n;
+       string roman;
+       switch (n) {
+       //special cases
+       case 900: 
+               roman = "CM";
+               break;
+       case 400:
+               roman = "CD";
+               break;
+       default:
+               if (val >= 100) {
+                       int hundreds = val / 100;
+                       roman = hunds[hundreds - 1];
+                       val = val % 100;
+               }
+               if (val >= 10) {
+                       switch (val) {
+                       //special case
+                       case 90:
+                               roman = roman + "XC";
+                               val = 0; //skip next
+                               break;
+                       default:
+                               int tensnum = val / 10;
+                               roman = roman + tens[tensnum - 1];
+                               val = val % 10;
+                       } // end switch
+               } // end tens
+               if (val > 0)
+                       roman = roman + ones[val -1];
+       }
+       docstring retval = from_ascii(roman);
+       return lowercase ? support::lowercase(retval) : retval;
 }
 
 
-docstring const romanCounter(int const n)
+docstring const lowerromanCounter(int const n)
 {
-       static char const * const roman[20] = {
-               "I",   "II",  "III", "IV", "V",
-               "VI",  "VII", "VIII", "IX", "X",
-               "XI",  "XII", "XIII", "XIV", "XV",
-               "XVI", "XVII", "XVIII", "XIX", "XX"
-       };
-
-       if (n < 1 || n > 20)
-               return from_ascii("??");
-       return from_ascii(roman[n - 1]);
+       return romanCounter(n, true);
 }
 
 } // namespace anon