如何在PHP中将JSON转为数组？json_decode()函数的正确用法

json_decode()

json_decode()

mixed json_decode ( string $json [, bool $assoc = false [, int $depth = 512 [, int $options = 0 ]]] )

$json_string = '{"name":"John Doe", "age":30, "city":"New York"}';

// 转换为关联数组
$array = json_decode($json_string, true);

// 转换为对象
$object = json_decode($json_string);

echo $array['name']; // 输出: John Doe
echo $object->name;  // 输出: John Doe

json_decode()

null

json_last_error()

json_last_error_msg()

$invalid_json = '{"name":"John Doe", "age":30, "city":"New York"'; // 缺少闭合括号

$result = json_decode($invalid_json, true);

if ($result === null) {
    echo 'JSON解码错误: ' . json_last_error_msg();
}

json_decode()

$nested_json = '{"name":"Jane Doe", "address":{"street":"123 Main St", "city":"Anytown"}}';

$nested_array = json_decode($nested_json, true);

echo $nested_array['address']['city']; // 输出: Anytown

$nested_object = json_decode($nested_json);

echo $nested_object->address->city; // 输出: Anytown

json_decode()

$unicode_json = '{"city":"北京"}';
$unicode_array = json_decode($unicode_json, true);

echo $unicode_array['city']; // 输出: 北京

utf8_encode()

utf8_decode()

json_decode()

JSON Streaming Parser

json_decode()

Undefined index

Trying to get property of non-object

isset()

array_key_exists()

$data = json_decode($json_string, true);

if (isset($data['name'])) {
    echo $data['name'];
} else {
    echo 'Name not found';
}

property_exists()

isset()

$data = json_decode($json_string);

if (property_exists($data, 'name')) {
    echo $data->name;
} else {
    echo 'Name not found';
}

// 或者使用 isset()，但要注意它对值为 null 的属性返回 false
if (isset($data->name)) {
    echo $data->name;
}

??

echo $data['name'] ?? 'Unknown'; // 如果 'name' 不存在，则输出 'Unknown'
echo $data->name ?? 'Unknown';  // 如果 'name' 不存在，则输出 'Unknown'