使用 php 通过 POST 提交多维数组

you could submit all parameters with such naming:

params[0][topdiameter]
params[0][bottomdiameter]
params[1][topdiameter]
params[1][bottomdiameter]

then later you do something like this:

foreach ($_REQUEST['params'] as $item) {
echo $item['topdiameter'];
echo $item['bottomdiameter'];
}

On submitting, you would get an array as if created like this:

$_POST['topdiameter'] = array( 'first value', 'second value' );
$_POST['bottomdiameter'] = array( 'first value', 'second value' );

However, I would suggest changing your form names to this format instead:

name="diameters[0][top]"
name="diameters[0][bottom]"
name="diameters[1][top]"
name="diameters[1][bottom]"
...

Using that format, it's much easier to loop through the values.

if ( isset( $_POST['diameters'] ) )
{
echo '<table>';
foreach ( $_POST['diameters'] as $diam )
{
// here you have access to $diam['top'] and $diam['bottom']
echo '<tr>';
echo '  <td>', $diam['top'], '</td>';
echo '  <td>', $diam['bottom'], '</td>';
echo '</tr>';
}
echo '</table>';
}

I made a function which handles arrays as well as single GET or POST values

function subVal($varName, $default=NULL,$isArray=FALSE ){ // $isArray toggles between (multi)array or single mode


$retVal = "";
$retArray = array();


if($isArray) {
if(isset($_POST[$varName])) {
foreach ( $_POST[$varName] as $var ) {  // multidimensional POST array elements
$retArray[]=$var;
}
}
$retVal=$retArray;
}


elseif (isset($_POST[$varName]) )  {  // simple POST array element
$retVal = $_POST[$varName];
}


else {
if (isset($_GET[$varName]) ) {
$retVal = $_GET[$varName];    // simple GET array element
}
else {
$retVal = $default;
}
}


return $retVal;


}

Examples:

$curr_topdiameter = subVal("topdiameter","",TRUE)[3];
$user_name = subVal("user_name","");

I know this is necro-posting, but I have been running to this same issue and ending up to this same answer many, many, many times, over some years.

Today though I had an additional issue, I wanted my users to be able to add as many items as they want, as well as rearrange their input before submitting, so I came up with this relatively clean solution:

$diameters = [];
foreach($_POST['diameters'] as $k=>$v){
$val = intdiv($k,2);
$diameters[$val][key($v)]=$v[key($v)];
}
$_POST['diameters']=$diameters;

The hard coded 2 is because that is the size of the input block (topdiameter, bottomdiameter)

So the html can simply look like this:

<tr>
<td><input name="diameters[][top]" type="text" [..] /></td>
<td><input name="diameters[][bottom]" type="text" [..] /></td>
</tr>
<tr>
<td><input name="diameters[][top]" type="text" [..] /></td>
<td><input name="diameters[][bottom]" type="text" [..] /></td>
</tr>

This way you will end up having a simple array in the format of:

$_POST['diameters']=[
["top"=>"","bottom"=>""],
["top"=>"","bottom"=>""],
...
]

Which should make whatever you need to do with your data much simpler.

@DisgruntledGoat 's answer is absolutely correct; however, in case anyone is looking for values that are not set to required, meaning $_POST === null could happen, you would use the isset() conditional as such:

$placeHolderValue = "Incomplete";


if ( isset( $_POST['diameters'] ) )
{
echo '<table>';
foreach ( $_POST['diameters'] as $diam )
{
// here you have access to $diam['top'] and $diam['bottom']
echo '<tr>';
if (isset($diam['top'])) {
echo '  <td>' . $diam['top'] . '</td>';
} else {
echo '<td>' . $placeHolderValue . '</td>';
if (isset($diam['top'])) {
echo '  <td>' . $diam['bottom'] . '</td>';
} else {
echo '<td>' . $placeHolderValue . '</td>';
echo '</tr>';
}
echo '</table>';
}

This all using the naming format that @DisgruntledGoat mentioned in their answer.