When PHP is developed, when you use empty to check the results returned by a function, you will get an error: Fatal error:can ' t usage function return value in write context
For example, the following code:
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<?php
echo Empty (strlen (' Test '));
Go to the PHP manual to see where the empty function describes the following text:
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Note:empty () Only checks variables as anything else would result in a parse error. In other words, the following won't Work:empty (Trim ($name)).
Come to the conclusion: empty () Only detect variables, detection of any variables will cause parsing error!
Therefore, we can not take empty to directly detect the value returned by the function, the above example solution is as follows:
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<?php
$length = strlen (' test ');
echo Empty ($length);
