Question

How can I add new data to a JSON structure?

Here is the JSON in json.txt:

[
 {"name":"foo","number":"1"},
 {"name":"bar","number":"2"},
 {"name":"Hello","number":"3"}
]

Now I want to add a new line {"name":"good day","number":"**"}

$file = 'json.txt';
$data = json_decode(file_get_contents($file));
$newdata = array('name'=>'good day', 'number' => '**');// how to add `number` automatic `+1`, make it to `4` with php code?
$data[] = $newdata;
file_put_contents($file, json_encode($data));

Answer 1

$file = 'json.txt';
$data = json_decode(file_get_contents($file));
$newNumber = max(array_map(
   function($e) {return intval($e['number']);},
$data)) + 1;
$newdata = array('name'=>'good day', 'number' => strval($newNumber));
$data[] = $newdata;
file_put_contents($file, json_encode($data));

In php < 5.3, replace the $newNumber = statement with:

$newNumber = max(array_map(
    create_function('$e', 'return intval($e["number"]);'),
$data)) + 1;