Compare the differences between json_encode and json_decode

Four basic principles of JSON

1.json_decode()

json_decode
(PHP 5 >= 5.2.0, PECL json >= 1.2.0)

json_decode — Characters in JSON format String encoding

Description
mixed json_decode (string $json [, bool $assoc])
Accepts a JSON format string and converts it into a PHP variable

Parameters

json
The string in json string format to be decoded.

assoc
When this parameter is TRUE, array will be returned instead of object.


Return value
Returns an object or if the optional assoc parameter is TRUE, an associative array is instead returned.

Example

Example #1 json_decode Example of ()

Copy the code as follows:

$json = '{"a":1,"b":2 ,"c":3,"d":4,"e":5}';
var_dump(json_decode($json));
var_dump(json_decode($json, true));
?>

The above example will output:

Copy the code as follows:

object(stdClass)#1 ( 5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
}

array(5) {
["a" ] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int (4)
["e"] => int(5)
}

Copy the code code as follows:

$data='[{"Name":"a1","Number":"123","Contno":"000","QQNo":""},{"Name":"a1" ,"Number":"123","Contno":"000","QQNo":""},{"Name":"a1","Number":"123","Contno":"000", "QQNo":""}]';
echo json_decode($data);

The result is:

Copy the code as follows:

Array ( [0] => stdClass Object ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) [1] => stdClass Object ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) [2] => stdClass Object ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) )

It can be seen that the objects compiled by json_decode() are now output as json_decode ($data,true) Try

Copy the code as follows:

echo json_decode($data,true);

Result:

Copy the code code as follows:

Array ( [0] => Array ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) [1] => Array ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) [2] => Array ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) )

It can be seen that json_decode($data,true) outputs an associative array. It can be seen that json_decode($data) outputs an object, and json_decode("$arr",true) forces it to generate a PHP associative array.

2.json_encode()

json_encode
(PHP 5 >= 5.2.0, PECL json >= 1.2.0)

json_encode — JSON the variable Encoding

Report a bug Description
string json_encode (mixed $value [, int $options = 0 ] )
Return the JSON form of value

Report a bug Parameters

value
The value to be encoded can be any data type except resource type

This function can only accept UTF-8 encoded data

options
Binary mask consisting of the following constants: JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_NUMERIC_CHECK, JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT, JSON_UNESCAPED_UNICODE.

Report a bug Return value
Encoding If successful, a JSON format is returned. Represents a string or returns FALSE on failure.

Report a bug Update log
Version Description
5.4.0 options parameter constants added: JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, and JSON_UNESCAPED_UNICODE.
5.3.3 The options parameter adds a constant: JSON_NUMERIC_CHECK.
5.3.0 Add options parameter.


Report a bug Example

Example #1 A json_encode() example

Copy code code as follows:

$arr ​​= array ('a'=>1,'b'=>2,'c'=>3,'d'=>4, 'e'=>5);

echo json_encode($arr);
?>

The above routine will output:

Copy code The code is as follows:

{"a":1,"b":2,"c":3,"d":4,"e":5}

Example #2 Usage of options parameter in json_encode() function

Copy the code The code is as follows:

$a = array('',"'bar'",'"baz"','&blong&', "\xc3\xa9");

echo "Normal: ", json_encode($a), "\n";
echo "Tags: ", json_encode($a, JSON_HEX_TAG), "\n";
echo "Apos: ", json_encode($a, JSON_HEX_APOS ), "\n";
echo "Quot: ", json_encode($a, JSON_HEX_QUOT), "\n";
echo "Amp: ", json_encode($a, JSON_HEX_AMP), "\n" ;
echo "Unicode: ", json_encode($a, JSON_UNESCAPED_UNICODE), "\n";
echo "All: ", json_encode($a, JSON_HEX_TAG | JSON_HEX_APOS | JSON_HEX_QUOT | JSON_HEX_AMP | JSON_UNESCAPED_UNICODE), "\ n\n";

$b = array();

echo "Empty array output as array: ", json_encode($b), "\n";
echo " Empty array output as object: ", json_encode($b, JSON_FORCE_OBJECT), "\n\n";

$c = array(array(1,2,3));

echo "Non-associative array output as array: ", json_encode($c), "\n";
echo "Non-associative array output as object: ", json_encode($c, JSON_FORCE_OBJECT), "\n\ n";

$d = array('foo' => 'bar', 'baz' => 'long');

echo "Associative array always output as object: ", json_encode($d), "\n";
echo "Associative array always output as object: ", json_encode($d, JSON_FORCE_OBJECT), "\n\n";
?>

The above routine will output:

Copy the code as follows:

Normal: [""," 'bar'","\"baz\"","&blong&","\u00e9"]
Tags: ["\u003Cfoo\u003E","'bar'","\"baz\""," &blong&","\u00e9"]
Apos: ["","\u0027bar\u0027","\"baz\"","&blong&","\u00e9"]
Quot: ["","'bar'","\u0022baz\u0022","&blong&","\u00e9"]
Amp: ["","'bar'"," \"baz\"","\u0026blong\u0026","\u00e9"]
Unicode: ["","'bar'","\"baz\"","&blong&", "é"]
All: ["\u003Cfoo\u003E","\u0027bar\u0027","\u0022baz\u0022","\u0026blong\u0026","é"]

Empty array output as array: []
Empty array output as object: {}

Non-associative array output as array: [[1,2,3]]
Non-associative array output as object : {"0":{"0":1,"1":2,"2":3}}

Associative array always output as object: {"foo":"bar","baz ":"long"}
Associative array always output as object: {"foo":"bar","baz":"long"}

Example #3 Continuous and Non-consecutive array example

Copy the code as follows:

echo "Continuous array".PHP_EOL;
$sequential = array( "foo", "bar", "baz", "blong");
var_dump(
$sequential,
json_encode($sequential)
);

echo PHP_EOL. "Nonsequential array".PHP_EOL;
$nonsequential = array(1=>"foo", 2=>"bar", 3=>"baz", 4=>"blong");
var_dump(
$nonsequential,
json_encode($nonsequential)
);

echo PHP_EOL."A non-continuous array generated by deleting a continuous array value".PHP_EOL;
unset($sequential[1]);
var_dump(
$sequential,
json_encode($sequential)
);
?>

The above routine will output:

Copy the code code as follows:

Continuous array
array(4) {
[0]=>
string(3) "foo"
[1]=>
string(3 ) "bar"
[2]=>
string(3) "baz"
[3]=>
string(5) "blong"
}
string (27) "["foo","bar","baz","blong"]"

Non-continuous array
array(4) {
[1]=>
string(3) "foo"
[2]=>
string(3) "bar"
[3]=>
string(3) "baz"
[ 4]=>
string(5) "blong"
}
string(43) "{"1":"foo","2":"bar","3":"baz ","4":"blong"}"

A non-continuous array generated by deleting a continuous array value
array(3) {
[0]=>
string (3) "foo"
[2]=>
string(3) "baz"
[3]=>
string(5) "blong"
}
string(33) "{"0":"foo","2":"baz","3":"blong"}"

Copy the code as follows:

$obj->Name= 'a1';$obj->Number ='123';
$obj->Contno= '000';
echo json_encode($obj);

The result is:

Copy the code as follows:

{" Name":"a1",
"Number":"123",
"Contno":"000"
}

You can see json_encode() and json_decode() are the compilation and decompilation process. Note that json only accepts utf-8 encoded characters, so the parameters of json_encode() must be utf-8 encoded, otherwise you will get empty characters or null.

json
The string in json string format to be decoded.

assoc
When this parameter is TRUE, array will be returned instead of object.


Return value
Returns an object or if the optional assoc parameter is TRUE, an associative array is instead returned.

Example

Example #1 json_decode Example of ()

Copy the code as follows:

$json = '{"a":1,"b":2 ,"c":3,"d":4,"e":5}';
var_dump(json_decode($json));
var_dump(json_decode($json, true));
?>

The above example will output:

Copy the code as follows:

object(stdClass)#1 (5) {
["a"] => int(1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
}

array(5) {
["a"] => int( 1)
["b"] => int(2)
["c"] => int(3)
["d"] => int(4)
["e"] => int(5)
}

Copy the code The code is as follows:

$data='[{"Name ":"a1","Number":"123","Contno":"000","QQNo":""},{"Name":"a1","Number":"123","Contno" :"000","QQNo":""},{"Name":"a1","Number":"123","Contno":"000","QQNo":""}]';
echo json_decode($data);

The result is:

Copy the code as follows:

Array ( [0] => stdClass Object ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) [1] => stdClass Object ( [Name] => a1 [Number] => ; 123 [Contno] => 000 [QQNo] => ) [2] => stdClass Object ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] = > ) )

It can be seen that the object compiled by json_decode() is an object. Now try to output json_decode($data,true)

Copy the code as follows:

echo json_decode($data,true);

Result:

Copy the code as follows:

Array ( [ 0] => Array ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) [1] => Array ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) [2] => Array ( [Name] => a1 [Number] => 123 [Contno] => 000 [QQNo] => ) )

It can be seen that json_decode($data,true) outputs an associative array. From this, it can be seen that json_decode($data) outputs an object, and json_decode("$arr",true) forces it to generate a PHP associative array. .

2.json_encode()

json_encode
(PHP 5 >= 5.2.0, PECL json >= 1.2.0)

json_encode — Yes Variables are JSON encoded

Report a bug Description
string json_encode (mixed $value [, int $options = 0 ] )
Return the JSON form of value

Report a bug Parameters

value
The value to be encoded can be any data type except the resource type

This function can only accept UTF-8 encoded data

options
Binary mask consisting of the following constants: JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_NUMERIC_CHECK, JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT, JSON_UNESCAPED_UNICODE.

Report a bug Return value
If encoding is successful, return one A string represented as JSON or FALSE on failure.

Report a bug Update log
Version Description
5.4.0 options parameter constants added: JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, and JSON_UNESCAPED_UNICODE.
5.3.3 The options parameter adds a constant: JSON_NUMERIC_CHECK.
5.3.0 Add options parameter.


Report a bug Example

Example #1 A json_encode() example

Copy the code as follows:

$arr ​​= array ('a'=>1,'b'=>2,'c'=>3,'d'=> 4,'e'=>5);

echo json_encode($arr);
?>

The above routine will output:

Copy code The code is as follows:

{"a":1,"b":2,"c":3,"d":4,"e":5}

Example #2 Usage of options parameter in json_encode() function

Copy the code as follows:

$a = array(' ',"'bar'",'"baz"','&blong&', "\xc3\xa9");

echo "Normal: ", json_encode($a), "\ n";
echo "Tags: ", json_encode($a, JSON_HEX_TAG), "\n";
echo "Apos: ", json_encode($a, JSON_HEX_APOS), "\n";
echo "Quot: ", json_encode($a, JSON_HEX_QUOT), "\n";
echo "Amp: ", json_encode($a, JSON_HEX_AMP), "\n";
echo "Unicode: ", json_encode($a, JSON_UNESCAPED_UNICODE), "\n"; #$b = array();

echo "Empty array output as array: ", json_encode($b), "\n";
echo "Empty array output as object: ", json_encode( $b, JSON_FORCE_OBJECT), "\n\n";

$c = array(array(1,2,3));

echo "Non-associative array output as array: ", json_encode($c), "\n";
echo "Non-associative array output as object: ", json_encode($c, JSON_FORCE_OBJECT), "\n\n";

$ d = array('foo' => 'bar', 'baz' => 'long');

echo "Associative array always output as object: ", json_encode($d), "\ n";
echo "Associative array always output as object: ", json_encode($d, JSON_FORCE_OBJECT), "\n\n";
?>


The above routine Will output:

Copy the code code as follows:

Normal: ["","'bar'","\"baz\"","&blong&","\u00e9"]
Tags: ["\u003Cfoo\u003E ","'bar'","\"baz\"","&blong&","\u00e9"]
Apos: ["","\u0027bar\u0027","\"baz\ "","&blong&","\u00e9"]
Quot: ["","'bar'","\u0022baz\u0022","&blong&","\u00e9"]
Amp: ["","'bar'","\"baz\"","\u0026blong\u0026","\u00e9"]
Unicode: [""," 'bar'","\"baz\"","&blong&","é"]
All: ["\u003Cfoo\u003E","\u0027bar\u0027","\u0022baz\u0022","\ u0026blong\u0026","é"]

Empty array output as array: []
Empty array output as object: {}

Non-associative array output as array: [[ 1,2,3]]
Non-associative array output as object: {"0":{"0":1,"1":2,"2":3}}

Associative array always output as object: {"foo":"bar","baz":"long"}
Associative array always output as object: {"foo":"bar","baz":"long"}

Example #3 Example of continuous and non-continuous arrays

Copy the code as follows:

echo "Continuous Array" .PHP_EOL;
$sequential = array("foo", "bar", "baz", "blong");
var_dump(
$sequential,
json_encode($sequential)
);

echo PHP_EOL."Nonsequential array".PHP_EOL;
$nonsequential = array(1=>"foo", 2=>"bar", 3=>"baz" , 4=>"blong");
var_dump(
$nonsequential,
json_encode($nonsequential)
);

echo PHP_EOL."Delete a continuous array value Non-continuous array generated by ".PHP_EOL;
unset($sequential[1]);
var_dump(
$sequential,
json_encode($sequential)
);
? >

The above routine will output:

Copy the code as follows:

Continuous array
array(4) {
[0]=>
string(3) "foo"
[1]=>
string(3) "bar"
[2]=>
string(3 ) "baz"
[3]=>
string(5) "blong"
}
string(27) "["foo","bar","baz","blong "]"

Non-continuous array
array(4) {
[1]=>
string(3) "foo"
[2]=>
string(3) "bar"
[3]=>
string(3) "baz"
[4]=>
string(5) "blong"
}
string(43) "{"1":"foo","2":"bar","3":"baz","4":"blong"}"

Delete one A non-continuous array generated by the method of continuous array values ​​
array(3) {
[0]=>
string(3) "foo"
[2]=>
string (3) "baz"
[3]=>
string(5) "blong"
}
string(33) "{"0":"foo","2": "baz","3":"blong"}"

Copy the code. The code is as follows:

$obj->Name= 'a1'; $obj->Number ='123';
$obj->Contno= '000';
echo json_encode($obj);

The result is:

Copy the code as follows:

{"Name":"a1",
"Number":"123",
"Contno":"000"
}

It can be seen that json_encode() and json_decode() are compilation and decompilation processes. Note that json only accepts utf-8 encoded characters, so the parameters of json_encode() must be utf-8 encoded. , otherwise you will get an empty character or null.

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