Morse Code encoder/decoder

Morse code is a method for transmitting information, using standardized sequences of short and long elements, for the letters, numerals, punctuation and special characters of a message. The short and long elements can be formed by sounds, marks or pulses, and are commonly known as "dots" and "dashes" or "dits" and "dahs". There are short spaces between the dits and dahs within a character, longer ones between characters, and still longer ones between words.

Read more here

PHP:

$lettertomorse=array(
     "a" => ".-",
     "b" => "-...",
     "c" => "-.-.",
     "d" => "-..",
     "e" => ".",
     "f" => "..-.",
     "g" => "--.",
     "h" => "....",
     "i" => "..",
     "j" => ".---",
     "k" => ".-.",
     "l" => ".-..",
     "m" => "--",
     "n" => "-.",
     "o" => "---",
     "p" => ".--.",
     "q" => "--.-",
     "r" => ".-.",
     "s" => "...",
     "t" => "-",
     "u" => "..-",
     "v" => "...-",
     "w" => ".--",
     "x" => "-..-",
     "y" => "-.--",
     "z" => "--..",
     "1" => ".----",
     "2" => "..---",
     "3" => "...--",
     "4" => "....-",
     "5" => ".....",
     "6" => "-....",
     "7" => "--...",
     "8" => "---..",
     "9" => "----.",
     "0" => "-----",
     " " => "   ",
     "." => ".-.-.-",
     "," => "--..--",
     "EOM" => ".-.-."
     );
 
 $morsetoletter=array();
 reset($lettertomorse);
 foreach($lettertomorse as $letter => $code) 
 {
     $morsetoletter[$code]=$letter;
 }
 
 function morse_encode($txt) 
 {
     global $lettertomorse;
 
     $line="";
     for ($i=0;$i<strlen($txt);$i++) 
     {
         $letter=substr($txt,$i,1);
 
         // ignore unknown characters
         if (empty($lettertomorse[$letter])) 
             continue;
 
         $line.=$lettertomorse[$letter]." ";
     }
     return $line;
 }
 
 function morse_decode($string) 
 {
     global $morsetoletter;
 
     $line="";
     $letters=array();
     $letters=explode(" ",$string);
     foreach ($letters as $letter) 
     {
         // ignore unknown characters
         if (empty($letter)) 
             $line.=" ";
         if (empty($morsetoletter[$letter])) 
             continue;
 
         $line.=$morsetoletter[$letter];
     }
     return $line;
 }
 

Example usage:

PHP:

print morse_encode("I Am Fine");