为什么“”不是空的？

I am trying this code:

<?php
$form = $_POST['myformdata'];

class validacoes {

    function validate_year($form) {
        $input_datas = $form['data'];
        foreach($input_datas as $val){
            if($val>1930 && $val<2012){
                echo "correct";
            }
            else
            echo "bad"; //show bad bad

        }
    }
}

$val = new validacoes();

$data = array();
var_dump($form['data']);


try {
    if (!empty($form['data'])){// why this is true ?
    $data['livre'] = $val->validate_year($form);
    }
    else
    echo "empty"; 
} catch (Exception $e) {
    $data['livre'] = $e->getMessage();
}

echo json_encode($data);

?>

//var_dump

var_dump($form['data']);

    array
      0 => string '' (length=0)
      1 => string '' (length=0)

Why the function validate_year($form) is running without any input ? should be empty, correct ?

It is not empty -- it is an array with 2 empty elements.

You posted the information yourself. $form['data'] contains an array of two objects. Therefore it isn't empty.

Maybe you want

if (!empty($form['data'][0]) && !empty($form['data'][1]))