php json转换相关知识(小结)

$a = [\'aa\', \'bb\', \'cc\'];
$ret = json_encode($a);
var_dump($ret);

$a = [ \'a\' => \'aa\', \'b\' => \'bb\', \'c\' => \'cc\'];
$ret = json_encode($a);
var_dump($ret);

$a = [ 0 => \'aa\', 1 => \'bb\', 2 => \'cc\'];
$ret = json_encode($a);
var_dump($ret);

$a = [ 2 => \'aa\', 3 => \'bb\', 4 => \'cc\'];
$ret = json_encode($a);
var_dump($ret);

$a = [\'aa\', \'bb\', \'cc\'];
$ret = json_encode($a, JSON_FORCE_ );
var_dump($ret); 

$ret = ( )$a; // 强制将php数组变成了php对象
var_dump($ret); 
$ret = json_encode($ret); // 将php对象转换成json对象
var_dump($ret);

$str = \'{\"name\":\"zhangsan\", \"age\": 18}\';
$ret2 = json_decode($str, true);
var_dump($ret2);

$str = \'[\"q\", \"w\", \"e\"]\';
$ret = json_decode($str, true);
var_dump($ret);

array(2) {
 [\"name\"]=>
 string(8) \"zhangsan\"
 [\"age\"]=>
 int(18)
}
array(3) {
 [0]=>
 string(1) \"q\"
 [1]=>
 string(1) \"w\"
 [2]=>
 string(1) \"e\"
}

$str = \'{\"name\":\"zhangsan\", \"age\": 18}\';
$ret = json_decode($str);
var_dump($ret);

var_dump($ret->name);

 (stdClass)#1 (2) {
 [\"name\"]=>
 string(8) \"zhangsan\"
 [\"age\"]=>
 int(18)
}
string(8) \"zhangsan\"

class TestJson {
    const CONST_VALUE_A = \'aaa\';
    public $b = \'bbb\';
    protected $c = \'ccc\';
    private $d = \'ddd\';
    public function hello() {

        print_r(\"hello\\n\");
    }
    public static $stValue = \'st\';

}

$test = new TestJson();
var_dump($ret);
$ret = json_encode($test);
var_dump($ret);

// 存数据
$raw = file_get_contents(\'php://input\');
$param = json_decode($raw, true);
var_dump($param);
$s = json_encode($param);
var_dump($s); 

……
// 将$s存到了数据库表对应字段里面
……
……

// 取数据
$column = json_deocde($c, true);
$resp = [
 \'status\' => 0,
 \'column\' => $column,
];
echo json_encode($resp);

// 取数据
$column = json_deocde($c, true);
if (empty($column)) {
 $column = ( )$column; // 强制将php空数组变成了php对象
}
$resp = [
 \'status\' => 0,
 \'column\' => $column,
];
echo json_encode($resp);