php函数之strtr和str_replace的用法详解以及效率分析 原创

<?php
  //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
  echo "<br>";

  //实例二：数组的键值用字符串替换
  $arr = array("blue","red","green","yellow");
  $str1 = str_replace("red","pink",$arr,$count);
  print_r($str1);
  //输出结果
  //Array ( [0] => blue [1] => pink [2] => green [3] => yellow ) 
  echo "<br>" . $count; //输出替换次数1

  //实例三：数组替换数组，一一映射替换
  $arr1 = array("banana","orange");
  $arr2 = array("pitaya","tomato");
  $con_arr = array("apple","orange","banana","grape");
  $con_rep = str_replace($arr1,$arr2,$con_arr,$count1);
  print_r($con_rep);
  //输出结果
  // Array ( [0] => apple [1] => tomato [2] => pitaya [3] => grape ) 
  echo "<br>" . $count1; //输出替换次数2

  //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,$count2);
  print_r($new_arr);
  //输出结果
  //Array ( [0] => tomato [1] => apple [2] => orange [3] => tomato ) 
  echo "<br>" . $count2; //输出替换次数2
?>

<?php
  	//用法一：strtr(string,from,to)
	echo strtr("I Love you","Lo","lO");
	/*输出结果：
	I lOve yOu
	you中的o被替换了，很诡异，要注意可能；
	这种用法也不能被替换为空，不生效；
	不推荐使用该方法*/

	//用法二：strtr(string,array)
	$arr = array("Hello" => "Hi", "world" => "earth");
	echo strtr("Hello world",$arr);
	/*输出结果：
	Hi earth*/
?>