XHTML 1.0验证 - PHP代码行引发错误。 为什么？ 怎么修？

Question

I'm working on a school project in PHP and my web pages have to pass XHTML 1.0 Validation.

The following line of code throws errors.

<img src="<?php echo './img/'. dayOfWeek(). '.png'?>" alt="<?php echo dayOfWeek() ?>" />

Error Line 116, Column 18: Unescaped '<' not allowed in attributes values

<img src="<?php echo './img/'. dayOfWeek(). '.png'?>" alt="<?php echo d…

✉

Error Line 116, Column 18: attributes construct error

<img src="<?php echo './img/'. dayOfWeek(). '.png'?>" alt="<?php echo d…

✉

Error Line 116, Column 18: Couldn't find end of Start Tag img line 116

<img src="<?php echo './img/'. dayOfWeek(). '.png'?>" alt="<?php echo d…

Any suggestions as to why this is happening and how to fix will be much appreciated.

Answer 1

Error handling is important. Hopefully this code based on mature live platform will help you.

<?php
error_reporting(E_ALL);

//No errors if live, outputs errors if local testing.
ini_set('display_errors', substr($_SERVER['HTTP_HOST'],0,4)=='www.' ? 0 : 1);

//Use an include and put the error handling function there.
set_error_handler('error_handle');

function error_handle($errno,$errstr,$errfile,$errline)
{
 //Quick dump.
 //You should store all errors (HTTP, JavaScript, PHP and SQL) in logs.
 echo '<div><p>errno = '.$errno.'</p></div>';
 echo '<div><p>errstr = '.errstr.'</p></div>';
 echo '<div><p>errfile = '.$errfile.'</p></div>';
 echo '<div><p>errline = '.$errline.'</p></div>';
}
?>

Also ensure that your XHTML is XHTML by serving the correct mime header:

<?php
if (stristr($_SERVER['HTTP_ACCEPT'],'application/xhtml+xml'))
{
 $mime = 'application/xhtml+xml; charset=UTF-8';
}
else
{
 $mime = 'text/html; charset=UTF-8';//Not UTF-8 string for IE6 but no longer valid 2010+.
}

header('Content-Type: '.$mime);
?>

If you would like further insight in to XHTML5 (HTML5 using the XML parser) see my website in my profile; it's an entire web platform that uses this winning combination. Best of luck!