PHP中UTF8二进制及明文字符串的转化功能详解

<?php
define("b", "<br>");
$a = "FE";
$a1 = "FF";
$s = 16;
$e = 2;
echo $s . "进制的" . $a . "表示为" . $e . "进制是" . base_convert($a, $s, $e) . b;
echo $s . "进制的" . $a1 . "表示为" . $e . "进制是" . base_convert($a1, $s, $e) . b;
$str = "计算机rr我们是谁？";
$strlen = strlen($str);
$n = 0;
echo $str.'（二进制UTF-8表示）：'.b;
$str_bin='';
while ($n < $strlen)
{
  $t = ord($str[$n]);
  $stra=base_convert($t, 10, 2) ;
  if(strlen($stra)<8)
  {
    $stra="0".$stra;
  }
  $str_bin.=$stra;
  $n++;
}
echo $str_bin.b;//已经翻译为二进制了
$str_bin="1110100010101110101000011110011110101110100101111110011010011100101110100110000101110011111001101000100010010001111001001011101110101100111001101001100010101111111010001011000010000001111011111011110010011111"; //在此输入二进制，程序编码为明文输出
$chr='';
$str='';
for($i=0;$i<strlen($str_bin);$i++)
{
  $chr.=$str_bin[$i];
  if(($i+1)%8==0)
  {
    $str.=chr(base_convert($chr, 2, 10));
    $chr=NULL;
  }
}
echo $str;//二进制的UTF8原代码明文
?>

16进制的FE表示为2进制是11111110
16进制的FF表示为2进制是11111111
计算机rr我们是谁？（二进制UTF-8表示）：
1110100010101110101000011110011110101110100101111110011010011100101110100111001001110010111001101000100010010001111001001011101110101100111001101001100010101111111010001011000010000001111011111011110010011111
计算机as我们是谁？