/// <summary>
/// Converts a number 0 <= n <= 999 to its word representation by appending it to a StringBuilder.
/// The flag denotes if the function aborts if num == 0 and therefore does not append anything.
/// </summary>
/// <param name="flag">Denotes if the function aborts if num == 0.</param>
/// <param name="num">Number which gets converted.</param>
/// <param name="str">StringBuilder to which result is appended.</param>
/// <returns>True, if something was appended.</returns>
public static bool AppendToFlag(bool flag, uint num, StringBuilder str)
{
if (num > 999)
{
throw new ArgumentOutOfRangeException("num", "Argument must be within 0 and 999");
}
// shortcut:
if (num == 0 && flag)
{
return(false);
}
if (num < 100)
{
UpToTwoDigits(num, str);
return(true);
}
// 100 <= num <= 999
uint hundreds = num / 100; // this is >= 1 and <= 9
str.Append(Numerals.LowAsString(hundreds));
str.Append(" hundred");
uint tens = num % 100;
// add tens if neccessary:
if (tens != 0)
{
str.Append(" ");
UpToTwoDigits(tens, str);
}
return(true);
}
/// <summary>
/// Converts a number 0 <= n <= 99 to its word representation.
/// </summary>
private static void UpToTwoDigits(uint num, StringBuilder str)
{
if (num > 99)
{
throw new ArgumentOutOfRangeException("num", "Argument must be within 0 and 99");
}
// shortcut:
if (num <= 19)
{
str.Append(Numerals.LowAsString(num));
return;
}
// 20 <= num <= 99
uint tens = num / 10; // this is something >= 2 and <= 9 ---> tens-2 is index in HighNumerals
uint ones = num % 10; // this is something between 0 and 9
str.Append(Numerals.HighAsString(tens - 2));
if (ones != 0) // avoid ninety-zero, instead: ninety
{
str.Append("-");
str.Append(Numerals.LowAsString(ones));
}
}
