soundex

Description

Calculates the soundex key of str.

Soundex keys have the property that words pronounced similarly produce the same soundex key, and can thus be used to simplify searches in databases where you know the pronunciation but not the spelling. This soundex function returns a string 4 characters long, starting with a letter.

This particular soundex function is one described by Donald Knuth in "The Art Of Computer Programming, vol. 3: Sorting And Searching", Addison-Wesley (1973), pp. 391-392.

Example 1. Soundex Examples <?php soundex("Euler")      == soundex("Ellery");    // E460 soundex("Gauss")      == soundex("Ghosh");    // G200 soundex("Hilbert")    == soundex("Heilbronn"); // H416 soundex("Knuth")      == soundex("Kant");      // K530 soundex("Lloyd")      == soundex("Ladd");      // L300 soundex("Lukasiewicz") == soundex("Lissajous"); // L222 ?>

See also levenshtein(), metaphone(), and similar_text().