php怎么实现数据替换

// 参数 $search,要替换的字符串，或数组
 
// 参数 $replace,被用来替换的字符串或数组
 
// 参数 $subject,被查询的字符串或数组
 
// 参数 $count，可选，如果被指定，将为设置为替换的次数
 
// 返回值：该函数返回替换后的数组或者字符串(新生成的)
 
 
  //实例一：字符串替换字符串
  $str1 = str_replace("red","black","red green yellow pink purple");
  echo $str1."";  //输出结果为black green yellow pink purple
 
  //实例二：字符串替换数组键值
  $arr = array("blue","red","green","yellow");
  $str1 = str_replace("red","pink",$arr,$i);
  print_r($str1);
 
  //实例三：数组替换数组，映射替换
  $arr1 = array("banana","orange");
  $arr2 = array("pitaya","tomato");
  $con_arr = array("apple","orange","banana","grape");
  $con_rep = str_replace($arr1,$arr2,$con_arr,$count);
  print_r($con_rep);
 
  //实例四：如$search为数组，$replace为字符串时
  $search = array("banana","grape");
  $replace = "tomato";
  $arr = array("banana","apple","orange","grape");
  $new_arr = str_replace($search,$replace,$arr,$count);
  print_r($new_arr);