Understand the difference between json_encode and json_decode in PHP

##1. json_encode() JSON encodes variables

Syntax: json_encode($value[,$options=0])
• Note: 1. $value is the value to be encoded, and this function is only valid for UTF8 encoded data;
• ​ ​ ​ ​ ​ 2. options: a binary mask composed of the following constants: JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, ​​​​​​PRINT, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT;
  ​ ​ 3. The second parameter is generally not needed;
  ​​ 4. JSON data is actually a string, which can be printed out using var_dump() to see the data type;
  ​ 5. JSON data will be returned if the execution is successful, otherwise FALSE will be returned.
  

$book = array('a'=>'xiyouji','b'=>'sanguo','c'=>'shuihu','d'=>'hongloumeng');
$json = json_encode($book);
echo $json;

{"a":"xiyouji","b":"sanguo ","c":"shuihu","d":"hongloumeng"}

##2. json_decode() decodes JSON data and converts it into PHP variables

• Note: 1 , $json is the data to be decoded, which must be utf8-encoded data;
​​2. When the $assoc value is TRUE, it returns an array, and when it is FALSE, it returns an object;
• 3. $depth is the recursion depth;
  ​​4. $option binary mask, currently only supports JSON_BIGINT_AS_STRING;
  5. Generally, only the first two parameters are used. If you want data of a data type, add a parameter true.
  
  
Example:

$book = array('a'=>'xiyouji','b'=>'sanguo','c'=>'shuihu','d'=>'hongloumeng');
  $json = json_encode($book);
  
  $array = json_decode($json,TRUE);
  $obj = json_decode($json);
  var_dump($array);
  var_dump($obj);

The results printed by the browser are as follows:

object(stdClass)#2 (4) { ["a"]=> string(7) "xiyouji" ["b"]=> string(6) "sanguo" ["c"]= > string(6) "shuihu" ["d"]=> string(11) "hongloumeng" }

The two results don’t seem to be much different, but when the elements inside are called, The methods of array and obj are different.

$book = array('a'=>'xiyouji','b'=>'sanguo','c'=>'shuihu','d'=>'hongloumeng');
  $json = json_encode($book);
  
  $array = json_decode($json,TRUE);
  $obj = json_decode($json);
  var_dump($array['b']);//调用数组元素
  echo &#39;<br/>&#39;;
  var_dump($obj->c);//调用对象元素

The print result is as follows:

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