Fatal error: Can't use function return value in write context in /home/gdcrpgin/public_html/manage_mypage.php on line 79

Question

Fatal error: Can't use function return value in write context in /home/gdcrpgin/public_html/manage_mypage.php on line 79

The complete web project was working fine until it was on my local windows machine since i uploaded this to online linux server (Hostgator) one of my page started showing this error I don't have any idea what this error mean i tried troubleshooting it at my level but nothing was achieved.

Line 79 is

<input type="text" name="home" class="form-control" maxlength="60" value = "<?php if(!empty(getuserfield($conn,"home"))) echo getuserfield($conn,"home") ?>"  required>

Function getuserfield() return nothing more than "Fake" string. I commented out its actual work to see it helps or not but no luck.

function getuserfield($conn,$field)
{
    /*
    $table = $_SESSION['type'];
    $key = $_SESSION['key'];
    $user = $_SESSION['username'];  
    $query = "select $field from $table where $key = '$user'";  
    $query_run = mysqli_query($conn,$query) or die(mysqli_error($conn));    
    while($fetch = mysqli_fetch_array($query_run)){
    if(!empty($fetch[0]))
        return $fetch[0];
    else
        return null;
    }*/
    return "Fake";
}

Answer 1

One google query about your problem got me the the solution to your problem (probably). If this is indeed the answer, you're probably guilty of not doing any research before coming here, shame.

You can find the solution here: Can't use method return value in write context

You're probably running an old version of php. This seems VERY likely since your application used to work, and now it doesn't on a "new" environment. The function empty() (so it's not about your getuserfield()) can only accept expressions since PHP 5.5.

So to fix your problem, install a newer version of PHP.

Answer 2

empty is used to test whether a variable doesn't exist or is falsey. You're using it on the return value of a function. Those are incompatible uses. Get rid of empty, you don't need it here. if (getuserfield(..)) does exactly the same thing for a function.

It happens to work on another server because since PHP 5.5, empty also accepts expressions of any sort. One of your servers has PHP 5.5, the other something older. Though empty is still used superfluously here.

You should always be aware of the PHP version you're using to develop, where you're going to deploy to, and that both should be identical or at least the same major release version.