Weird PHP error Can t use function return value in write context

Question

I m getting this error and I can t make head or tail of it   The exact error message is      Fatal error  Can t use function return   value in write context in    home curricle public html descarga index php   on line 48   Line 48 is   if  isset   POST  sms code      TRUE       What could be going on here   Here s the full function   function validate sms code           state   NOTHING SUBMITED       if  isset   POST  sms code      TRUE              sms code   clean up   POST  sms code              return code   get sepomo code  sms code            switch  return code               case 1                no error              state   CORRECT CODE              break             case 2                 code already used              state   CODE ALREADY USED              break             case 3                 wrong code              state   WRONG CODE              break             case 4                 generic error              state   UNKNOWN SEPOMO CODE              break             default                 unknown error              state   UNKNOWN SEPOMO CODE              throw new Exception  Unknown sepomo code       return code               break                   else            state   NOTHING SUBMITED            dispatch on state  state

User · Answer

This can happen in more than one scenario, below is a list of well known scenarios :

// calling empty on a function 
empty(myFunction($myVariable)); // the return value of myFunction should be saved into a variable
// then you can use empty on your variable

// using parenthesis to access an element of an array, parenthesis are used to call a function

if (isset($_POST('sms_code') == TRUE ) { ...
// that should be if(isset($_POST['sms_code']) == TRUE)

This also could be triggered when we try to increment the result of a function like below:

$myCounter = '356';

$myCounter = intVal($myCounter)++; // we try to increment the result of the intVal...
// like the first case, the ++ needs to be called on a variable, a variable should hold the the return of the function then we can call ++ operator on it.

User · Answer

You mean  if  isset   POST  sms code       TRUE       though incidentally you really mean  if  isset   POST  sms code

User · Answer

This also happens when using empty on a function return    empty trim  someText   and doSomething     because empty is not a function but a language construct  not sure   and it only takes variables   Right     empty  someVar    Wrong     empty someFunc      Since PHP 5 5  it supports more than variables  But if you need it before 5 5  use trim  name     false  From empty documentation

User · Answer

i also ran into this problem due to syntax error  Using     instead of     in array index      foreach  arr parameters as  arr key  gt  arr value             arr named parameters    arr key      arr value

User · Answer

This error is quite right and highlights a contextual syntax issue  Can be reproduced by performing any kind  non-assignable  syntax  For instance   function Syntax  hello         then attempt to call the function as though a property and assign a value      this- Syntax  Hello      World     The above error will be thrown because syntactially the statement is wrong  The right assignment of  World  cannot be written in the context you have used  i e  syntactically incorrect for this context    Cannot use function return value  or it could read  Cannot assign the right-hand value to the function because its read-only   The specific error in the OPs code is as highlighted  using brackets instead of square brackets

User · Answer

if  isset   POST  sms code      TRUE       change this line to   if  isset   POST  sms code       TRUE       You are using parentheseis    for   POST but you wanted square brackets         OR  if  isset   POST  sms code     amp  amp    POST  sms code         this lets in this block only if   POST  sms code   has some value

User · Answer

Another scenario where this error is trigered due syntax error   ucwords  variable     string

User · Answer

Can be cause by wrong operator     when it should be     if mysql num rows  result    1      return  result  else     return false    This code throws this error  Note that   is assignment operator and not comparison operator  Fix is to change   to

User · Answer

for WORDPRESS   instead of   if  empty get option  smth       should be   if   get option  smth

User · Answer

The problem is in the    you have to go     if  isset   POST  sms code      TRUE    by  if  isset   POST  sms code      TRUE

User · Answer

I also  had a similar problem like yours  The problem is that you are using an old php version  I have upgraded to PHP 5 6 and the problem no longer exist

User · Answer

Correct syntax  you had a missing parentheses in the end    if  isset   POST  sms code       TRUE                                     p s  you dont need     TRUE  part  because BOOLEAN  true false  is returned already

[php] Weird PHP error: 'Can't use function return value in write context'

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