PHP仅在提交表单之前注意到未定义的索引

Question

I am trying to do a simple value check from a form and I want to assign some variables the values entered by the user. I have done this form :

<form action="<?php echo $_SERVER['PHP_SELF'];?>" method="POST">
                <label for="raspuns1"><span class="glyphicon glyphicon-pencil"></span> Raspuns subpunct a</label>
                <input type="text" class="form-control" name="raspuns1" placeholder="Raspuns a"><br>
                <label for="raspuns2"><span class="glyphicon glyphicon-pencil"></span> Raspuns subpunct b</label>
                <input type="text" class="form-control" name="raspuns2" placeholder="Raspuns b"><br>
                <label for="raspuns3"><span class="glyphicon glyphicon-pencil"></span> Raspuns subpunct c</label>
                <input type="text" class="form-control" name="raspuns3" placeholder="Raspuns c"><br>
                <label for="raspuns4"><span class="glyphicon glyphicon-pencil"></span> Raspuns subpunct d</label>
                <input type="text" class="form-control" name="raspuns4" placeholder="Raspuns d"><br>
                <button type="submit" class="btn btn-success glyphicon glyphicon-check"> Verifica răspunsurile</button>
    </form>

and this is the php code

<?php 
$corect1="raspunsulcorect";
$corect2="raspunsulcorect";
$corect3="raspunsulcorect";
$corect4="raspunsulcorect";

if(isset($_POST['submit']))
{
$raspuns1=$_POST['raspuns1'];
$raspuns2=$_POST['raspuns2'];
$raspuns3=$_POST['raspuns3'];
$raspuns4=$_POST['raspuns4'];
}

?>

The problem is that when I open the page, it shows me

Notice: Undefined index: raspuns1 in A:\XAMPP\htdocs\Copie\Teste\test1-geometrie.php on line 5

Notice: Undefined index: raspuns2 in A:\XAMPP\htdocs\Copie\Teste\test1-geometrie.php on line 6

Notice: Undefined index: raspuns3 in A:\XAMPP\htdocs\Copie\Teste\test1-geometrie.php on line 7

Notice: Undefined index: raspuns4 in A:\XAMPP\htdocs\Copie\Teste\test1-geometrie.php on line 8

After pressing the submit button, everything is okay, but if the page is opened the first time, this will be shown. What am I doing wrong? That first if should not let the program check the variables

Answer 1

Go ahead and add a method which checks if this is a POST request before accessing the $_POST superglobal.

Example:

function isPost() {
  return strtolower($_SERVER['REQUEST_METHOD']) == 'post';
}

In your code (assuming you have defined the above function):

if(isPost() && isset($_POST['submit']))
{
$raspuns1=$_POST['raspuns1'];
$raspuns2=$_POST['raspuns2'];
$raspuns3=$_POST['raspuns3'];
$raspuns4=$_POST['raspuns4'];
}

Also check the filter_input and filter_var functions when fetching values from the $_GET and $_POST superglobals.