note 59782 added to function.is-null
| From: | jsjacobs at piercedmedia dot com | Date: | Thu, 15 Dec 2005 15:34:07 +0000 |
| Subject: | note 59782 added to function.is-null | ||
| Groups: | php.notes | ||
| Request: | Send a blank email to php-notes+get-100201@lists.php.net to get a copy of this message | ||
I have variables that may be set to empty ($test = "";) when passed into a fuction and as
such may be set, but not null, but still empty. I wanted to know the difference between these so I
created a test displaying all errors. (I hate even seeing notices).
first I check isset, is_null, and empty on an unset variable, then set the variable empty ($test =
"";)
<?php
error_reporting(2047);
if(is_null($test))
{
print 'This is Null<BR>';
}
else
{
print 'Not Null<BR>';
}
if(isset($test))
{
print 'This is Set<BR>';
}
else
{
print 'This is Not Set<BR>';
}
if(empty($test))
{
print 'This is Empty<BR>';
}
else
{
print 'This is Not Empty<BR>';
}
$test = '';
if(is_null($test))
{
print 'This is Null<BR>';
}
else
{
print 'This is Not Null<BR>';
}
if(isset($test))
{
print 'This is Set<BR>';
}
else
{
print 'This is Not Set<BR>';
}
if(empty($test))
{
print 'This is Empty<BR>';
}
else
{
print 'This is Not Empty<BR>';
}
?>
And the results
----------------------------------------------
Notice: Undefined variable: test in /var/www/htdocs/test.php on line 4
This is Null
This is Not Set
This is Empty
This is Not Null
This is Set
This is Empty
We can conclude that is_null will error on an unset variable, and thus is not the same as isset.
----
Manual Page -- http://www.php.net/manual/en/function.is-null.php
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