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The Match Rating codex of one name.

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

Parameters — value is a single name: any alphabetic character — a letter, a letter number, or a mark the Unicode Alphabetic property takes in, such as a Devanagari vowel sign — plus a space is accepted; a digit, punctuation or any other whitespace is refused rather than ignored. Case does not matter: the name is uppercased by the full case mapping, so ß reads as SS. The string overload forwards to the span one.

Returns — string, an uppercase code, or the empty string when value is empty. A code over six UTF-8 bytes keeps its first three and last three characters.

Exceptions — ArgumentNullException when value is null (the string overload only). ArgumentException when value holds a character that is neither alphabetic nor a space.

Example — doubles collapse before non-leading vowels are dropped, and a code over six characters keeps only its first three and last three.

using Lodestar.Text.Phonetics;

string smith = MatchRatingApproach.Codex("Smith");             // => SMTH
string mississippi = MatchRatingApproach.Codex("Mississippi"); // => MSSP
string bhattacharya = MatchRatingApproach.Codex("Bhattacharya");   // => BHTHRY

Remarks — Mississippi reducing to MSSP is doubled letters collapsing before the non-leading vowels between them are dropped: the raw sequence M-I-S-S-I-S-S-I-P-P-I collapses its adjacent-letter runs first (M-I-S-I-S-I-P-I), and only then loses every vowel but the first character, whatever it is — a leading vowel is kept, as in Codex("aeiou") → "A".

Bhattacharya reducing to six characters (BHTCHRY would be seven) keeps its first three and its last three: BHT + HRY. The six is counted in UTF-8 bytes, as jellyfish counts it, so a four-character name outside ASCII can be truncated too, and repeat its middle: Codex("並丝七世") is 並丝七丝七世, jellyfish's own answer (decision 0009).

A character that is neither alphabetic nor a space throws instead of being dropped — Codex("O'Brien") and Codex("Anne-Marie") both raise ArgumentException, naming the character that stopped them — where Compare answers null for the same input. Soundex.Encode, Metaphone.Encode and Nysiis.Encode accept it, each by its own rule; all four are jellyfish's.

Applies to — net10.0, netstandard2.0.

See also — MatchRatingApproach, MatchRatingApproach.Compare, the phonetics index.