PHP字符串和十六进制如何实现互相转换

<?php
/**
 *字符串转十六进制函数
 *@pream string $str='abc';
 */
function strToHex($str) {
  $hex = "";
  for ($i = 0;$i < strlen($str);$i++) $hex.= dechex(ord($str[$i]));
  $hex = strtoupper($hex);
  return $hex;
}
?>

<?php
/**
 *十六进制转字符串函数
 *@pream string $hex='616263';
 */
function hexToStr($hex) {
  $str = "";
  for ($i = 0;$i < strlen($hex) - 1;$i+= 2) $str.= chr(hexdec($hex[$i] . $hex[$i + 1]));
  return $str;
}
?>

<?php
class Test {
  /**
   *字符串转十六进制函数
   *@pream string $str='abc';
   */
  public function strToHex($str) {
    $hex = "";
    for ($i = 0;$i < strlen($str);$i++) $hex.= dechex(ord($str[$i]));
    $hex = strtoupper($hex);
    return $hex;
  }
  /**
   *十六进制转字符串函数
   *@pream string $hex='616263';
   */
  public function hexToStr($hex) {
    $str = "";
    for ($i = 0;$i < strlen($hex) - 1;$i+= 2) $str.= chr(hexdec($hex[$i] . $hex[$i + 1]));
    return $str;
  }
} < spanstyle = "white-space:pre" > < / span > //测试Demo效果
$test = new Test();
$str = '要加密的内容sxfenglei';
$data = $test->strToHex($str);
echo '加密内容:要加密的内容sxfenglei <br>' . $data . '<hr>';
$output = $test->hexToStr($data);
echo '解密内容:E8A681E58AA0E5AF86E79A84E58685E5AEB9737866656E676C6569 <br>' . $output;
?>