function line_search($array,$tar)

 {

     if(!is_array($array) || count($array) < 1) return false;

     for($i=0;$i<count($array);$i++){

         if($array[$i] == $tar){

             return $i;

         }

     }

     return false;

 }

 line_search($arr,34);

 // 非递归

 function binary_search($array,$tar)

 {

     if(!is_array($array) || count($array) < 1) return false;

         // 数组必须排序

     sort($array);

     $high = count($array) - 1;

     $low = 0;

     while($low <= $high){

         $middle = intval(($high + $low) / 2);

         if($array[$middle] > $tar){

             $high = $middle - 1;

         }elseif($array[$middle] < $tar){

             $low = $middle + 1;

         }else{

             return $middle;

         }

     }

     return false;

 }

 binary_search($arr,165.4);

 // 递归

 function binary_search($array,$tar,$high=0,$low=0)

 {

     if(!is_array($array) || count($array) < 1) return false;

     sort($array);

     if($low <= $high){

         $middle = intval(($high + $low) / 2);

         if($array[$middle] > $tar){

             $high = $middle - 1;

             echo $high."</br>";

             return binary_search($array,$tar,$high,$low);

         }elseif($array[$middle] < $tar){

             $low = $middle + 1;

             return binary_search($array,$tar,$high,$low);

         }else{

             return $middle;

         }

     }

     return false;

 }

 binary_search($arr,125,count($arr),0);