RosettaCodeData/Task/Number-names/D/number-names.d

79 lines
2.6 KiB
D

import std.stdio, std.array, std.algorithm, std.bigint, std.range;
immutable tens = ["", "", "twenty", "thirty", "forty",
"fifty", "sixty", "seventy", "eighty", "ninety"];
immutable small = ["zero", "one", "two", "three", "four", "five",
"six", "seven", "eight", "nine", "ten", "eleven",
"twelve", "thirteen", "fourteen", "fifteen",
"sixteen", "seventeen", "eighteen", "nineteen"];
immutable huge = ["", ""] ~ ["m", "b", "tr", "quadr", "quint",
"sext", "sept", "oct", "non", "dec"]
.map!q{ a ~ "illion" }.array;
string spellBigInt(BigInt n) pure /*nothrow @safe*/ {
static string nonZero(string c, BigInt n, string connect="") pure /*nothrow @safe*/ {
return (n == 0) ? "" : (connect ~ c ~ n.spellBigInt);
}
static string lastAnd(string num) pure /*nothrow*/ @safe {
if (num.canFind(',')) {
string pre = num.retro.find(',').retro[0 .. $ - 1];
string last = num[pre.length + 1 .. $];
if (!last.canFind(" and "))
last = " and" ~ last;
num = pre ~ ',' ~ last;
}
return num;
}
static string big(in uint e, in BigInt n) pure /*nothrow @safe*/ {
switch (e) {
case 0: return n.spellBigInt;
case 1: return n.spellBigInt ~ " thousand";
default: return n.spellBigInt ~ " " ~ huge[e];
}
}
if (n < 0) {
return "minus " ~ spellBigInt(-n);
} else if (n < 20) {
return small[n.toInt];
} else if (n < 100) {
immutable BigInt a = n / 10;
immutable BigInt b = n % 10;
return tens[a.toInt] ~ nonZero("-", b);
} else if (n < 1_000) {
immutable BigInt a = n / 100;
immutable BigInt b = n % 100;
return small[a.toInt] ~ " hundred" ~ nonZero(" ", b, " and");
} else {
string[] bigs;
uint e = 0;
while (n != 0) {
immutable BigInt r = n % 1_000;
n /= 1_000;
if (r != 0)
bigs ~= big(e, r);
e++;
}
return lastAnd(bigs.retro.join(", "));
}
}
version(number_names_main) {
void main() {
foreach (immutable n; [0, -3, 5, -7, 11, -13, 17, -19, 23, -29])
writefln("%+4d -> %s", n, n.BigInt.spellBigInt);
writeln;
auto n = 2_0121_002_001;
while (n) {
writefln("%-12d -> %s", n, n.BigInt.spellBigInt);
n /= -10;
}
writefln("%-12d -> %s", n, n.BigInt.spellBigInt);
writeln;
}
}