php and form field array names

HeidiR

Guys, I'm trying to understand how to use and reference a form field that has an array name in php. I have the code below and the outpot below.

<?php
define('HOST', $_SERVER['HTTP_HOST']);
define('URI', rtrim(dirname($_SERVER['PHP_SELF']), '/\\'));
define('BASE_URL', "http://" . HOST . URI . "/test.php");

$str .= "<form action='" . BASE_URL . "' method='post' name='f1'>";

$str .= "<input type='text' name='testfld[]' size=3><br>";
$str .= "<input type='text' name='testfld[]' size=3><br>";
$str .= "<input type='text' name='testfld[]' size=3><br>";

$str .= "<br><input type='submit' name='btn' value='Go'>";

$str .= "</form>";

echo $str;

echo("<br>POST ");
var_dump($_POST);

if (is_array(testfld))
	echo("<br>testfld is array");
else
	echo("<br>testfld not array");


foreach($_POST as $key => $val) {
	echo("<br>" . $key . " - " . $val);
}

//echo("<br>testfld2: " . $_POST(['testfld[2]']));

?>

OUTPUT:

POST array(2) { ["testfld"]=> array(3) { [0]=> string(1) "a" [1]=> string(1) "b" [2]=> string(1) "c" } ["btn"]=> string(2) "Go" }
testfld not array
testfld - Array
btn - Go

It appears that $_POST correctly identifies the form field named "testfld" as an array. However, when I test the see if testfld is an array, php says that it is not. I would also like to reference each field in the "testfld" array. Tried using the code in the last echo (above) but received a syntax error.

Can someone point me in the right direction? What am I missing?

bradgrafelman

This:

is_array(testfld)

is testing to see if the [man]constant[/man] named "testfld" is an array. However, I doubt you've ever defined any such constant (at least, you sure haven't in any code you've shown us), thus PHP assumes you meant the string "testfld". But of course, a string isn't an array, thus the if() statement will always evaluate to false.

This:

echo("<br>testfld2: " . $_POST(['testfld[2]']));

Doesn't work for a couple of reasons:

$POST is an [man]array[/man], not a variable containing the name of a function, so doing $POST() doesn't make sense.
There won't be any index inside of the $_POST array named 'testfld[2]'. There will, however, be one named 'testfld' - the value at that index will be a numerically-indexed array. The value for array index 2 in that array will give you the string "c".

It looks like you might want to take a moment and find some very basic PHP tutorials to learn the basic syntax.

HeidiR

As a work-around to accessing a form field of type array within $_POST, I have found that assigning the from field of type array to a local var ($temp_ar), then accessing the desired cell by index as usual ($temp_ar[2])😉 works correctly.

However, still looking for the correct syntax to access a form field of type array within $POST directly. (e.g. $POST['testfld'][2]) //produces a syntax error)

<php>
<?php
define('HOST', $SERVER['HTTP_HOST']);
define('URI', rtrim(dirname($SERVER['PHP_SELF']), '/\'));
define('BASE_URL', "http://" . HOST . URI . "/test2.php");

$str .= "<form action='" . BASE_URL . "' method='post' name='f1'>";

$str .= "<input type='text' name='testfld[]' size=3 value='a'><br>";
$str .= "<input type='text' name='testfld[]' size=3 value='b'><br>";
$str .= "<input type='text' name='testfld[]' size=3 value='c'><br>";

$str .= "<br><input type='submit' name='btn' value='Go'>";

$str .= "</form>";

echo $str;

echo("<br>POST ");
var_dump($_POST);

if (is_array($_POST['testfld']))
echo("<br>testfld is array");
else
echo("<br>testfld not array");

echo("<br>testfld ar ");
foreach($_POST['testfld'] as $key => $val) {
echo("<br>" . $key . " - " . $val);
}

$temp_ar = $_POST['testfld'];
echo("<br>testfld2: " . $temp_ar[2]);

//echo("<br>testfld2: " . $_POST['testfld'][2]); //syntax error

?>
</php>

OUTPUT:
POST array(2) { ["testfld"]=> array(3) { [0]=> string(1) "a" [1]=> string(1) "b" [2]=> string(1) "c" } ["btn"]=> string(2) "Go" }
testfld is array
testfld ar
0 - a
1 - b
2 - c

testfld2: c

NogDog

I get no syntax error with that code (even after uncommenting the supposedly offending line).

HeidiR

Thanks. Tried it again id it worked. Look like the syntax $_POST['testfld'][2] is correct as it produces a value of 'c'.