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PHP ASCII碼與字符串的相互轉換

   [代碼]php代碼:

  <?php

  class ascii {

  /**

  * 將ascii碼轉為字符串

  * @param type $str 要解碼的字符串

  * @param type $prefix 前綴,默認:&#

  * @return type

  */

  function decode($str, $prefix="&#") {

  $str = str_replace($prefix, "", $str);

  $a = explode(";", $str);

  foreach ($a as $dec) {

  if ($dec < 128) {

  $utf .= chr($dec);

  } else if ($dec < 2048) {

  $utf .= chr(192 + (($dec - ($dec % 64)) / 64));

  $utf .= chr(128 + ($dec % 64));

  } else {

  $utf .= chr(224 + (($dec - ($dec % 4096)) / 4096));

  $utf .= chr(128 + ((($dec % 4096) - ($dec % 64)) / 64));

  $utf .= chr(128 + ($dec % 64));

  }

  }

  return $utf;

  }

  /**

  * 將字符串轉換為ascii碼

  * @param type $c 要編碼的字符串

  * @param type $prefix 前綴,默認:&#

  * @return string

  */

  function encode($c, $prefix="&#") {

  $len = strlen($c);

  $a = 0;

  while ($a < $len) {

  $ud = 0;

  if (ord($c{$a}) >= 0 && ord($c{$a}) <= 127) {

  $ud = ord($c{$a});

  $a += 1;

  } else if (ord($c{$a}) >= 192 && ord($c{$a}) <= 223) {

  $ud = (ord($c{$a}) - 192) * 64 + (ord($c{$a + 1}) - 128);

  $a += 2;

  } else if (ord($c{$a}) >= 224 && ord($c{$a}) <= 239) {

  $ud = (ord($c{$a}) - 224) * 4096 + (ord($c{$a + 1}) - 128) * 64 + (ord($c{$a + 2}) - 128);

  $a += 3;

  } else if (ord($c{$a}) >= 240 && ord($c{$a}) <= 247) {

  $ud = (ord($c{$a}) - 240) * 262144 + (ord($c{$a + 1}) - 128) * 4096 + (ord($c{$a + 2}) - 128) * 64 + (ord($c{$a + 3}) - 128);

  $a += 4;

  } else if (ord($c{$a}) >= 248 && ord($c{$a}) <= 251) {

  $ud = (ord($c{$a}) - 248) * 16777216 + (ord($c{$a + 1}) - 128) * 262144 + (ord($c{$a + 2}) - 128) * 4096 + (ord($c{$a + 3}) - 128) * 64 + (ord($c{$a + 4}) - 128);

  $a += 5;

  } else if (ord($c{$a}) >= 252 && ord($c{$a}) <= 253) {

  56 $ud = (ord($c{$a}) - 252) * 1073741824 + (ord($c{$a + 1}) - 128) * 16777216 + (ord($c{$a + 2}) - 128) * 262144 + (ord($c{$a + 3}) - 128) * 4096 + (ord($c{$a + 4}) - 128) * 64 + (ord($c{$a + 5}) - 128);

  $a += 6;

  } else if (ord($c{$a}) >= 254 && ord($c{$a}) <= 255) { //error

  $ud = false;

  }

  $scill .= $prefix.$ud.";";

  }

  return $scill;

  }

  }

  /*

  PHP 轉 ASCII

  require_once "ascii_class.php";

  */

  $aa = new ascii;

  echo "<xmp>";

  echo $str = $aa->encode("PHP二次開發:www.php2.cc");

  echo "</xmp>";

  echo $aa->decode($str);

  ?>

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