How to convert a base 10 number to alphabetic like ordered list in HTML

alphabetical, decimal, java, numeric

Solution

This is the basic algorithm. Use a StringBuffer if you need to be more efficient:

  public static String getAlpha(int num) {

    String result = "";
    while (num > 0) {
      num--; // 1 => a, not 0 => a
      int remainder = num % 26;
      char digit = (char) (remainder + 97);
      result = digit + result;
      num = (num - remainder) / 26;
    }

    return result;
  }

Another way to do this would be to convert to base 26, and then add 97 to each character in the string you get.

Problem

I want to convert a integer to alphabetic equivalent like ordered list in HTML. ``` <ol type="a"> ``` I tried to convert a base 10 number to a base 26 with a-z digits. But that's not what I wanted. ``` IN WANT GET ----------------------- 1 => a <= a 2 => b <= b 3 => c <= c 4 => d <= d 5 => e <= e 6 => f <= f 7 => g <= g 8 => h <= h 9 => i <= i 10 => j <= j 11 => k <= k 12 => l <= l 13 => m <= m 14 => n <= n 15 => o <= o 16 => p <= p 17 => q <= q 18 => r <= r 19 => s <= s 20 => t <= t 21 => u <= u 22 => v <= v 23 => w <= w 24 => x <= x 25 => y <= y 26 => z <= az 27 => aa <= aa 28 => ab <= ab 29 => ac <= ac ``` ``` private final static char[] digits = { '0' , 'a' , 'b' , 'c' , 'd' , 'e' , 'f' , 'g' , 'h' , 'i' , 'j' , 'k' , 'l' , 'm' , 'n' , 'o' , 'p' , 'q' , 'r' , 's' , 't' , 'u' , 'v' , 'w' , 'x' , 'y' , 'z' }; private static String numberToAlphaNumeric(long i, int radix) { char[] buf = new char[65]; int charPos = 64; boolean negative = (i < 0); if (!negative) { i = -i; } while (i <= -radix) { buf[charPos--] = digits[(int)(-(i % radix))]; i = i / radix; } buf[charPos] = digits[(int)(-i)]; if (negative) { buf[--charPos] = '-'; } return new String(buf, charPos, (65 - charPos)); } public static String numberToAlphaNumeric(long number) { ArrayList<String> list = new ArrayList<String>(); for( int j = 0; list.size() != number; j++ ) { String alpha = numberToAlphaNumeric( j, digits.length ); if(!alpha.contains( "0" )) { list.add( alpha ); } } return list.get( list.size()-1 ); } ``` My 2nd Idea: If I extend a new leading symbol to the digits and convert my number to a base 27 number, I have the new Symbol in every carry over which is wrong and I can filter these out. This is very inefficient and ugly, but I have no more ideas. What is the common way?

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