Transfer keys and values from a JSON to PHP variables

Question

How to transfer data from a JSON:

{"resultado":true,"cadastros":[{"id":"12345","nome":"Augusto","idade":"30"},{"id":"23411","nome":"Carlos","idade":"93"},{"id":"13451","nome":"Bruno","idade":"23"}],"mensagem":"Success"}

For variables in PHP resulting in:

`$id[0] = "12345"; $nome[0] = "Augusto"; $idade[0] = "30"; $id[1] = "23411"; $nome[1] = "Carlos"; $idade[1] = "93";`

and also the amount of records, which in total of this example are 3.

$registros = "3";

I tried using json_decode() along with foreach() but it didn’t work. I don’t know how to develop the logic.

<?php   
    $json = '{"resultado":true,"cadastros":[{"id":"12345","nome":"Augusto","idade":"30"},{"i‌​d":"23411","nome":"Carlos","idade":"93"},{"id":"13451","nome":"Bruno","idade":"23‌​"}],"mensagem":"Success"}'; 
    $a = json_decode($json, true); 
    echo $a;   
?> 

results in

Notice: Array to string Conversion in C: Program Files Easyphp-Devserver-14.1VC11 data localweb teste.php on line 4

Array line 4 is the echo $a;

Answer 1

Utilize json_decode with the second parameter "true", an associative array will be returned, i.e., items formed by a key pair and value, in which each key has an associated value.

An example, where $url is the json link.

$a_Dados = json_decode(file_get_contents($url), true);
echo $a_Dados["resultado"]; //true
echo $a_Dados["cadastros"][0]["id"]; //12345

If necessary, make one:

$a_Dados = json_decode(file_get_contents($url), true);
for($i=0; $i<count($a_Dados["cadastros"]); $i++){
    echo $a_Dados["cadastros"][$i]["id"];
}

If you have a json encoded variable, change the following line:

 $a_Dados = json_decode($variavel_codifica_json,true);