PHP提交表单后，我如何保持按钮的适当检查 - PHP after submit on a form how to I keep the button appropriate checked

我正在构建一个计算器，我几乎完成了。在我的表格上，我在顶部有两个单选按钮，用于S.a.E单位或公制单位。

当我单击"计算"时，计算器中的一切都正常，但我选中的单选按钮会返回到未选中状态。如果有人点击度量并点击提交，我如何在结果出来后检查度量单选按钮，SAE也是如此？

这是我的全部代码：

<?php
if (isset($_POST['units'])) $units = $_POST['units'];
if (isset($_POST['dia'])) $dia = $_POST['dia'];
if (isset($_POST['wt'])) $wt = $_POST['wt'];
if (isset($_POST['L'])) $L = $_POST['L'];
if (isset($_POST['num'])) $num = $_POST['num'];
if (isset($_POST['waste'])) $waste = $_POST['waste'];
if (isset($_POST['surface'])) $surface = $_POST['surface'];
$denom = ($units == "US" ? 12 : 100);
$coverage = ($units == "US" ? 1000 : 92.9);
//$measurements = ($units == "US" ? "in" : "cm");
$measurements == $units;
if($units == 'US')
$measurements = 'in';
else if($units == 'Metric')
$measurements = 'cm';
else 
$measurements = 'in or cm';
$length == $units;
if($units == 'US')
$length = 'feet';
else if($units == 'Metric')
$length = 'meters';
else 
$length = 'feet or meters';
$answer1 = pi() * ($dia / $denom) * $L * $num * ($waste + 1) / $coverage;
$answer2 = pi() * (($dia + ($wt * 2)) / $denom) * $L * $num * ($waste + 1) / $coverage;
//$answer = ($answer1 + $answer2);
$answer = ($answer);
if($surface == TRUE)
$answer = ($surface * ($waste + 1) / $coverage);
else 
$answer = ($answer1 + $answer2);
echo <<<_END
<form method='post' action=''>
<table border='0' width='500px' cellpadding='2' cellspacing='1' class="table">
<tr class="calcheading"><td><label><input type="radio" name="units" value="US" />S.A.E.        </label>
<label><input type="radio" name="units" value="Metric" />Metric</label> </td></tr>
<tr class="calcheading"><td colspan="2"><strong>ConBlock MIC Circular Surface     Area</strong></td></tr>
<tr class="calcrow"><td>Surface Area ($length):</td><td align="center"><input type='text' name='surface' value="$surface"/></td></tr>
<tr class="calcrow"><td>Diameter ($measurements):</td><td align="center"><input type='text' name='dia' value="$dia"/></td></tr>
<tr class="calcrow2"><td>Wall Thickness ($measurements):</td><td align="center"><input type='text' name='wt' value="$wt"/></td></tr>
<tr class="calcrow"><td>Section Length ($length):</td><td align="center"><input type='text' name='L' value="$L"/></td></tr>
<tr class="calcrow"><td>Number of Sections:</td><td align="center"><input type='text' name='num' value="$num"/></td></tr>
<tr class="calcrow"><td>Waste Variance % (Please add in decimal form):</td><td     align="center"><input type='text' name='waste' value="$waste"/></td></tr>
<tr class="submit"><td colspan="2"><input type='submit' value='Calculate'/></td></tr>
_END;
?>
<tr class="calcrow">
<td><i>Gallons Needed for Interior Coating:</td>
<td align="center"><input type="text" value="<?php echo round($answer1, 2)?>"></td></i>
</tr>
<tr class="calcrow">
<td><i>Gallons Needed for Exteror Coating:</td>
<td align="center"><input type="text" value="<?php echo round($answer2, 2)?>"></td></i>
</tr>
<tr class="calcrow">
<td><i>Total Gallons of ConBlock MIC needed:</td>
<td align="center"><input type="text" value="<?php echo round($answer, 2)?>"></td></i>
</tr>
</table>
</form>

我到处找答案，但我想我不太确定在这件事上该找什么。要了解我在这里的意思，请访问网址：

http://www.launchrun.com/consealtest/ConBlockMIC-circular.php

感谢任何能帮助我阐明这个问题的人！

<?php
function selected( $val = "")
{
    $units = isset( $_POST['units'] ) ? $_POST['units'] : null;
    echo ( $units == $val ) ? "CHECKED='CHECKED'" : "";
}
$units = isset( $_POST['units'] ) ? $_POST['units'] : null;
$dia = isset( $_POST['dia'] ) ? $_POST['dia'] : null;
$wt = isset( $_POST['wt'] ) ? $_POST['wt'] : null;
$L = isset( $_POST['L'] ) ? $_POST['L'] : null;
$num = isset($_POST['num']) ? $_POST['num'] : null;
$waste = isset($_POST['waste']) ? $_POST['waste'] : null;
$surface = isset($_POST['surface']) ? $_POST['surface'] : null;
$denom = ( ( $units == "US" ) ? 12 : 100 );
$coverage = ( ( $units == "US" ) ? 1000 : 92.9);

$measurements = 'in or cm';
if( $units == 'US' ){
    $measurements = 'in';
}
if($units == 'Metric')
{
    $measurements = 'cm';
}


if($units == 'US')
$length = 'feet';
else if($units == 'Metric')
$length = 'meters';
else 
$length = 'feet or meters';
$answer1 = pi() * ($dia / $denom) * $L * $num * ($waste + 1) / $coverage;
$answer2 = pi() * (($dia + ($wt * 2)) / $denom) * $L * $num * ($waste + 1) / $coverage;
$answer = ($answer1 + $answer2);
$answer = ($answer);
if($surface == TRUE)
$answer = ($surface * ($waste + 1) / $coverage);
else 
$answer = ($answer1 + $answer2);
?>
<form method='post' action=''>
<table border='0' width='500px' cellpadding='2' cellspacing='1' class="table">
<tr class="calcheading"><td><label>
<input type="radio" name="units" <?php selected("US")?> value="US" />S.A.E.</label>
<label>
<input type="radio" name="units"  <?php selected("Metric")?> value="Metric" />Metric</label> </td></tr>
<tr class="calcheading"><td colspan="2"><strong>ConBlock MIC Circular Surface     Area</strong></td></tr>
<tr class="calcrow"><td>Surface Area (<?php echo $length ?>):</td><td align="center"><input type='text' name='surface' value="<?php echo $surface ?>"/></td></tr>
<tr class="calcrow"><td>Diameter (<?php echo $measurements ?>):</td><td align="center"><input type='text' name='dia' value="<?php echo $dia ?>"/></td></tr>
<tr class="calcrow2"><td>Wall Thickness ($measurements):</td><td align="center"><input type='text' name='wt' value="<?php echo $wt ?>"/></td></tr>
<tr class="calcrow"><td>Section Length ($length):</td><td align="center"><input type='text' name='L' value="<?php echo $L ?>"/></td></tr>
<tr class="calcrow"><td>Number of Sections:</td><td align="center"><input type='text' name='num' value="<?php echo $num ?>"/></td></tr>
<tr class="calcrow"><td>Waste Variance % (Please add in decimal form):</td><td     align="center"><input type='text' name='waste' value="<?php echo $waste ?>"/></td></tr>
<tr class="submit"><td colspan="2"><input type='submit' value='Calculate'/></td></tr>
<tr class="calcrow">
<td><i>Gallons Needed for Interior Coating:</td>
<td align="center"><input type="text" value="<?php echo round($answer1, 2)?>"></td></i>
</tr>
<tr class="calcrow">
<td><i>Gallons Needed for Exteror Coating:</td>
<td align="center"><input type="text" value="<?php echo round($answer2, 2)?>"></td></i>
</tr>
<tr class="calcrow">
<td><i>Total Gallons of ConBlock MIC needed:</td>
<td align="center"><input type="text" value="<?php echo round($answer, 2)?>"></td></i>
</tr>
</table>
</form>

<input type="radio" name="units" <?php if (isset($_POST['units']) && $_POST['units'] == "Metric"){ print("checked='"checked'""); } ?> value="Metric" />

您可以这样做：

<?php
$units = null;
if (!empty($_POST)) {
    $units = $_POST['units'];
}
?>
<input type="radio" name="units" value="Metric" <?php echo (($units == 'Metric') ? 'checked="checked"' : ''); ?> />
<input type="radio" name="units" value="US" <?php echo (($units == 'US') ? 'checked="checked"' : ''); ?> />

通过检查units输入的值，我们可以确定输入元素上的checked属性是否应该存在。