$name = array(
    "self" => "wangzhengyi",
    "student" => array(
        "chenshan",
        "xiaolingang"
    ),
    "unkmow" => "chaikun",
    "teacher" => array(
        "huangwei",
        "fanwenqing"
    )
);

wangzhengyi,chenshan,xiaolingang,chaikun,huangwei,fanwenqing

function arrToStr ($array)
{
  // 定义存储所有字符串的数组
  static $r_arr = array();
  if (is_array($array)) {
    foreach ($array as $key => $value) {
      if (is_array($value)) {
        // 递归遍历
        arrToStr($value);
      } else {
        $r_arr[] = $value;
      }
    }
  } else if (is_string($array)) {
      $r_arr[] = $array;
  }
  //数组去重
  $r_arr = array_unique($r_arr);
  $string = implode(",", $r_arr);
  return $string;
}

<?php
$name = array(
    "self" => "wangzhengyi",
    "student" => array(
        "chenshan",
        "xiaolingang"
    ),
    "unkmow" => "chaikun",
    "teacher" => array(
        "huangwei",
        "fanwenqing"
    )
);
function arrToStr ($array)
{
  // 定义存储所有字符串的数组
  static $r_arr = array();
  if (is_array($array)) {
    foreach ($array as $key => $value) {
      if (is_array($value)) {
        // 递归遍历
        arrToStr($value);
      } else {
        $r_arr[] = $value;
      }
    }
  } else if (is_string($array)) {
      $r_arr[] = $array;
  }
  //数组去重
  $r_arr = array_unique($r_arr);
  $string = implode(",", $r_arr);
  return $string;
}
echo arrToStr($name);
?>

wangzhengyi,chenshan,xiaolingang,chaikun,huangwei,fanwenqing