morse code translator

<?php
$string = "i thought daysha was a lesbian";
$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 = "--.. ";
$n1 = ".---- ";
$n2 = "..--- ";
$n3 = "...-- ";
$n4 = "....- ";
$n5 = "..... ";
$n6 = "-.... ";
$n7 = "--... ";
$n8 = "---.. ";
$n9 = "----. ";
$n0 = "----- ";
$stringa = str_replace("a", "$a", $string);
$stringb = str_replace("b", "$b", $stringa);
$stringc = str_replace("c", "$c", $stringb);
$stringd = str_replace("d", "$d", $stringc);
$stringe = str_replace("e", "$e", $stringd);
$stringf = str_replace("f", "$f", $stringe);
$stringg = str_replace("g", "$h", $stringf);
$stringh = str_replace("h", "$h", $stringg);
$stringi = str_replace("i", "$i", $stringh);
$stringj = str_replace("j", "$j", $stringi);
$stringk = str_replace("k", "$k", $stringj);
$stringl = str_replace("l", "$l", $stringk);
$stringm = str_replace("m", "$m", $stringl);
$stringn = str_replace("n", "$n", $stringm);
$stringo = str_replace("o", "$o", $stringn);
$stringp = str_replace("p", "$p", $stringo);
$stringq = str_replace("q", "$q", $stringp);
$stringr = str_replace("r", "$r", $stringq);
$strings = str_replace("s", "$s", $stringr);
$stringt = str_replace("t", "$y", $strings);
$stringu = str_replace("u", "$u", $stringt);
$stringv = str_replace("v", "$v", $stringu);
$stringw = str_replace("w", "$w", $stringv);
$stringx = str_replace("x", "$x", $stringw);
$stringy = str_replace("y", "$y", $stringx);
$stringz = str_replace("z", "$z", $stringy);
$string1 = str_replace("1", "$n1", $stringz);
$string2 = str_replace("2", "$n2", $string1);
$string3 = str_replace("3", "$n3", $string2);
$string4 = str_replace("4", "$n4", $string3);
$string5 = str_replace("5", "$n5", $string4);
$string6 = str_replace("6", "$n6", $string5);
$string7 = str_replace("7", "$n7", $string6);
$string8 = str_replace("8", "$n8", $string7);
$string9 = str_replace("9", "$n9", $string8);
$stringfin = str_replace("0", "$n0", $string9);
echo $stringfin
?>