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The Metaphone code of one word.

public static string Encode(ReadOnlySpan<char> value)
public static string Encode(string value)

Parameters — value is a single word. Non-letters in it are ignored rather than rejected, and case does not matter. The string overload forwards to the span one.

Returns — string, a variable-length code drawn from B X S K J T F H L M N P R 0 W Y, or the empty string when value holds no letter.

Exceptions — ArgumentNullException when value is null (the string overload only; a ReadOnlySpan<char> cannot be null). An empty string is accepted and encodes to the empty string.

Example — the digraphs that make the alphabet look strange.

using Lodestar.Text.Phonetics;

string th = Metaphone.Encode("Thomas");  // => 0MS
string sh = Metaphone.Encode("Christina");  // => XRSTN
string silent = Metaphone.Encode("Knight");  // => NT

Remarks — 0 and X are not placeholders. 0 is the "th" sound and X the "sh" sound, both written as single characters so a code stays one character per sound. This is why a Metaphone code must never be shown to a user: 0MS is correct and unreadable.

Knight → NT is the behaviour that distinguishes this from the other two encoders, and it is also the reason to prefer it for ordinary English words over Soundex.Encode. Silent k, w, g and b are all handled, along with GH, DGE, -TION and the rest of the spellings English uses for sounds it does not write plainly.

Parity is claimed on real words only. The shared 402-word corpus contains random letter sequences, and on those jellyfish behaves in ways specific to its C implementation; decision 0005 is the reasoning, and the practical form of it is that a code for xhdzhumzj is not something this package promises to match.

Applies to — net10.0, netstandard2.0.

See also — Metaphone, Soundex.Encode, the phonetics index.