Error message Strict standards Only variables should be passed by reference

Question

el   array shift  instance- gt find        The above code somehow reports the strict standards warning  but this will not   function get arr        return array 1  2      el   array shift get arr       So when will it report the warning anyway

User · Answer

Consider the following code   error reporting E STRICT   class test       function test arr  amp  a            var dump  a             function get arr             return array 1  2             t   new test   t- gt test arr  t- gt get arr       This will generate the following output   Strict Standards  Only variables should be passed by reference in  test php  on line 14 array 2       0   gt    int 1     1   gt    int 2      The reason  The test  get arr   method is not a variable and under strict mode this will generate a warning  This behavior is extremely non-intuitive as the get arr   method returns an array value   To get around this error in strict mode  either change the signature of the method so it doesn t use a reference   function test arr  a        var dump  a       Since you can t change the signature of array shift you can also use an intermediate variable    inter   get arr     el   array shift  inter

User · Answer

instance- gt find   returns a reference to a variable   You get the report when you are trying to use this reference as an argument to a function  without storing it in a variable first   This helps preventing memory leaks and will probably become an error in the next PHP versions   Your second code block would throw an error if it wrote like  note the  amp  in the function signature    function  amp get arr        return array 1  2      el   array shift get arr       So a quick  and not so nice  fix would be    el   array shift  tmp    instance- gt find         Basically  you do an assignment to a temporary variable first and send the variable as an argument

User · Answer

The cause of the error is the use of the internal PHP programming data structures function  array shift    php net end    The function takes an array as a parameter  Although an ampersand is indicated in the prototype of array shift   in the manual   there isn t any cautionary documentation following in the extended definition of that function  nor is there any apparent explanation that the parameter is in fact passed by reference   Perhaps this is  understood   I did not understand  however  so it was difficult for me to detect the cause of the error   Reproduce code   function get arr         return array 1  2      array   get arr     el   array shift  array

User · Answer

The second snippet doesn t work either and that s why   array shift is a modifier function  that changes its argument  Therefore it expects its parameter to be a reference  and you cannot reference something that is not a variable  See Rasmus  explanations here  Strict standards  Only variables should be passed by reference

User · Answer

Well  in obvious cases like that  you can always tell PHP to suppress messages by using     in front of the function    monthly index    array shift unpack  H    date  m Y        It may not be one of the best programming practices to suppress all errors this way  but in certain cases  like this one  it comes handy and is acceptable    As result  I am sure your friend  system administrator   will be pleased with a less polluted error log

User · Answer

This code    monthly index   array shift unpack  H    date  m Y        Need to be changed into    date time   date  m Y     unpack   unpack  H     date time   array shift  unpack

[php] Error message "Strict standards: Only variables should be passed by reference"

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