php中compact,extract,list函数的使用

<?php
//compact 将变量组合为数组
$key_1 = "val_1";
$key_2 = "val_2";
$data = array('$key_3'=>'val_3','$key_4'=>'val_4');
$arr_n =compact('key_1','key_2','data');
echo "compact:\n";
//extract根据键名导出变量
echo "extract:\n";
$arr_str = array('key_a'=>'val_a','key_b'=>'val_b','key_arr'=>array('1','2','3'));
extract($arr_str);
var_dump($key_a);
var_dump($key_b);
var_dump($key_arr);
// list(只作用于索引数组)用来取出数据。可只取出部分数据，如只取出前两个
echo "list:\n";
$arr_data =array('data_1','data_2','data_3','data_4');
list($v1,$v2)=$arr_data;
var_dump($v1);
var_dump($v2);
//list也可取变量放在数组指定位置中
list($data_res['0'],$data_res['5'])=$arr_data;
var_dump($data_res);
?>

compact 多个变量转数组

//多个变量转数组
    $name='phpff';
    $email='phpff@phpff.com';
    $info=compact('name','email');//传递变量名
    print_r($info);
    /*
    Array
    (
        [name] => phpff
        [email] => phpff@phpff.com
    )
    */

extract 数组转多个变量

//数组转多个变量
    $capitalcities['England'] = 'London';
    $capitalcities['Scotland'] = 'Edinburgh';
    $capitalcities['Wales'] = 'Cardiff';
    extract($capitalcities);//转变成三个变量 England，Scotland，Wales
    print $Wales;//Cardiff

$my_array = array("a" => "Cat","b" => "Dog", "c" => "Horse");

extract($my_array);
echo "$a = $a; $b = $b; $c = $c";

结果

$a = Cat; $b = Dog; $c = Horse