php 在php中回显会话变量
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Echoing session variables in php
提问by doxguy
I know that in php I can put a variable name inside a quoted string when I use echo, but I apparently can't do this with a session variable. Can anyone explain why?
我知道在 php 中，当我使用 echo 时，我可以将变量名放在带引号的字符串中，但显然我不能用会话变量来做到这一点。谁能解释为什么？
Here is the code, with the "offending" php commented out:
这是代码，注释掉了“违规”的 php：
<?php
session_start();
$test = 100;
$_SESSION['test'] = 200;
?>
<html>
<head>
<title>Test</title>
</head>
<body>
<p><?php echo($test."<br />");?></p>
<p><?php echo("$test"."<br />");?></p>
<p><?php echo($_SESSION['test']."<br />");?></p>
<p><?php //echo("$_SESSION['test']"."<br />");?></p>
</body>
</html>
And the output looks like this:
输出如下所示：
100
100
200
But if I uncomment the offending code line:
但是，如果我取消注释有问题的代码行：
<p><?php echo("$_SESSION['test']"."<br />");?></p>
I get no output and the following error:
我没有输出和以下错误：
Parse error: syntax error, unexpected T_ENCAPSED_AND_WHITESPACE, expecting T_STRING or T_VARIABLE or T_NUM_STRING in - on line 14
So I can go on my merry way knowing how to do it correctly (just keep the session variable outside of the double quotes), but I would really like to understand why this doesn't work for session variables.
所以我可以继续我的快乐方式，知道如何正确地做到这一点（只需将会话变量保留在双引号之外），但我真的很想理解为什么这对会话变量不起作用。
Thanks!
谢谢！
回答by Michael Berkowski
Inside a double-quoted string you must enclose a complex variable (array or object property) in {}:
在双引号字符串中，您必须将复杂变量（数组或对象属性）包含在{}：
<p><?php echo("{$_SESSION['test']}"."<br />");?></p>
This isn't an issue with $_SESSIONspecifically, but any array accessed by quoted keys. Note, that you caninclude a numerically indexed array value with wrapping in {}, as in "echo $array[2] is two";
这不是特别的问题$_SESSION，而是由带引号的键访问的任何数组。请注意，您可以包含一个数字索引的数组值，并用 换行{}，如"echo $array[2] is two";
