简述PHP_SELF参数
本文简述PHP_SELF参数的含义，并运用该参数将具有多个功能的php程序合并到一个文件中，这是一种常用的方法。
变量 $_SERVER[‘PHP_SELF’] 包含了当前php文件的相对访问路径，在form表单中将action参数设置为它，可以实现对当前php文件提交申请。结合if判断即可组合多功能到同一个php文件中。使用PHP_SELF的好处是不用担心修改php文件名导致程序无法正常运行，从而使代码始终保持通用性。
if 判断条件中可以使用 isset() 函数判断任意一个表单项是否存在于 $_GET 或$_POST数组中，如果存在表示用户已经提交了请求，否则表示用户初次访问该页面。以此实现同一php文件中不同功能的流量控制。
以下程序组合了多个功能，首页为功能选择页，每个功能还需要实现表单输入页和最终结果页。因此使用两层嵌套判断用户当前所在页面。
我还为表单添加了onsubmit属性，其中使用自定义函数beforeSubmit()判断用户的表单输入是否为空，若有任意项目为空则告警并返回false，表单不会继续执行action操作。
<!DOCTYPE html>
<html>
<head>
<title>Combinational Function</title>
<script type="text/javascript">
function beforeSubmit()
{
var input_boxes = document.getElementsByTagName("input");
for (var b = 0; b < input_boxes.length; b++)
{
if (! input_boxes[b].value)
{
alert("User input cannot be empty.")
return false;
}
}
return true;
}
</script>
</head>
<body>
<?php
if (isset($_GET['mode']))
{
$mode = $_GET['mode'];
switch ($mode)
{
case 'temp':
echo '<h1>Temperature Conversion Page</h1>';
if (isset($_GET['temp']))
{
$c = $_GET['temp'];
$f = ($c * 9 / 5) + 32;
echo ($c . " degrees Celsius is " . $f . " degrees Fahrenheit");
}
else
{
echo ' <p>Please enter a temperature in Celsius to convert to Fahrenheit</p>
<form action="' . $_SERVER['PHP_SELF'] . '" onSubmit="return beforeSubmit();">
<input type="hidden" name="mode" value="temp">
<input type="text" name="temp" id="temp" />
<input type="submit" value="Convert" />
</form>';
}
break;
case 'circle':
echo '<h1>Calculate Circle</h1>';
if (isset($_GET['radius']))
{
$r = $_GET['radius'];
$s = pi() * pow($r, 2);
$c = 2 * pi() * $r;
echo ('Radius of the circle: ' . $r . '<br>');
echo ('Area: ' . round($s, 2) . '<br>');
echo ('Circumference: ' . round($c, 2));
}
else
{
echo ' <p>Please enter the radius of a circle</p>
<form action="' . $_SERVER['PHP_SELF'] . '" onSubmit="return beforeSubmit();">
<input type="hidden" name="mode" value="circle">
<input type="text" name="radius" />
<input type="submit" value="Calculate" />
</form>';
}
break;
case 'sphere':
echo '<h1>Calculate Sphere</h1>';
if (isset($_GET['radius']))
{
$r = $_GET['radius'];
$s = 4 * pi() * pow($r, 2);
echo ('Radius of the sphere: ' . $r . '<br>');
echo ('Surface area: ' . round($s, 2) . '<br>');
}
else
{
echo ' <p>Please enter the radius of a Sphere</p>
<form action="' . $_SERVER['PHP_SELF'] . '" onSubmit="return beforeSubmit();">
<input type="hidden" name="mode" value="sphere">
<input type="text" name="radius" />
<input type="submit" value="Calculate" />
</form>';
}
break;
case 'cylinder':
echo '<h1>Calculate Cylinder</h1>';
if (isset($_GET['radius']))
{
$r = $_GET['radius'];
$h = $_GET['height'];
$s = 2 * pi() * pow($r, 2) + 2 * pi() * $r * $h;
echo ('The surface area of a cylinder with height ' . $h . ' and radius ' . $r . ' is ' . round($s, 2) . '.');
}
else
{
echo ' <form action="' . $_SERVER['PHP_SELF'] . '" onSubmit="return beforeSubmit();">
<input type="hidden" name="mode" value="cylinder">
The height:
<input type="text" name="height" /><br>
The radius:
<input type="text" name="radius" /><br>
<input type="submit" value="Calculate" />
</form>';
}
break;
case 'initials':
echo '<h1>Calculate Name</h1>';
if (isset($_GET['firstN']))
{
$first_name = $_GET['firstN'];
$surname = $_GET['surN'];
echo ('Your initials: ' . strtoupper(substr($first_name,0,1)) . '.' . strtoupper(substr($surname,0,1)) . '.');
}
else
{
echo ' <form action="' . $_SERVER['PHP_SELF'] . '" onSubmit="return beforeSubmit();">
<input type="hidden" name="mode" value="initials">
First Name:
<input type="text" name="firstN" /><br>
Surname:
<input type="text" name="surN" /><br>
<input type="submit" value="Calculate" />
</form>';
}
break;
case 'age':
echo '<h1>Judge Age</h1>';
if (isset($_GET['age']))
{
$age = $_GET['age'];
echo ($age > 17);
}
else
{
echo ' <p>Please enter your age</p>
<form action="' . $_SERVER['PHP_SELF'] . '" onSubmit="return beforeSubmit();">
<input type="hidden" name="mode" value="age">
<input type="text" name="age" />
<input type="submit" value="Judge" />
</form>';
}
break;
default:
echo '* Error: Unexpected argument.';
break;
}
}
else
{
echo ' <h1>Combinational Function</h1>
<form action="' . $_SERVER['PHP_SELF'] . '">
What would you want to do?
<br><br>
<select name="mode">
<option value="temp">Convert Temperature</option>
<option value="circle">Calculate Circle</option>
<option value="sphere">Calculate Sphere</option>
<option value="cylinder">Calculate Cylinder</option>
<option value="initials">Get Name Initials</option>
<option value="age">Judge Age</option>
</select>
<input type="submit" value="Do it!">
</form>';
}
?>
</body>
</html>
