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Function std.numeric.decimalToFactorial

This function transforms decimal value into a value in the factorial number system stored in fac.

ulong decimalToFactorial (
  ulong decimal,
  ref ubyte[21] fac
) pure nothrow @nogc @safe;

A factorial number is constructed as: fac[0] * 0! + fac[1] * 1! + ... fac[20] * 20!


decimal The decimal value to convert into the factorial number system.
fac The array to store the factorial number. The array is of size 21 as ulong.max requires 21 digits in the factorial number system.


A variable storing the number of digits of the factorial number stored in fac.


ubyte[21] fac;
size_t idx = decimalToFactorial(2982, fac);

writeln(fac[0]); // 4
writeln(fac[1]); // 0
writeln(fac[2]); // 4
writeln(fac[3]); // 1
writeln(fac[4]); // 0
writeln(fac[5]); // 0
writeln(fac[6]); // 0


Andrei Alexandrescu, Don Clugston, Robert Jacques, Ilya Yaroshenko


Boost License 1.0.