Description
string 
soundex ( string str )
     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 ?>
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     See also 
     levenshtein(),
     metaphone(), and 
     similar_text().