如何让PHP等待变量初始化？ [关闭]

Question

I need a PHP block to be run only when a variable is already set, do i need to do something with JavaScript or PHP is able to do it? Details: My variable is only set when the HTML form is submitted.

if(!empty($_FILES['file']['tmp_name'])){
    $caminho = $_FILES['file']['tmp_name'];
    $data = new Spreadsheet_Excel_Reader();
    $data->setOutputEncoding('CP1251');
    $data->read("$caminho");

    $conn = mysqli_connect("localhost","root","","pessoas");
    mysqli_select_db($conn,"pessoas");

    for ($x = 1; $x <= count($data->sheets[0]["cells"]); $x++) {
        $nome = $data->sheets[0]["cells"][$x][1];
        $matricula = $data->sheets[0]["cells"][$x][2];
        $nascimento = $data->sheets[0]["cells"][$x][3];
        $celular = $data->sheets[0]["cells"][$x][4];
        $sql = "INSERT INTO info (nome,matricula,datanasc,celular) 
        VALUES ('$nome','$matricula','$nascimento','$celular')";
    echo $sql."
";
    mysqli_query($conn, $sql);}
    }else {
    echo "Selecione um arquivo v&aacute;lido";
    }

Answer 1

You can check if the variable was set using the function isset

  if(isset($var)){
      // do something
  }